Danny Phantom/WMG

Danny absorbs powers from other ghosts.
As the theme song states, Danny originally only had invisibility, intangibility and flight, which have been shown to be standard powers for all ghosts, but picks up a veritable kaleidoscope of powers over the course of the series. This is due to the Ghost Portal giving him the ghost equivalent of a blank slate, a form that has no preference for any particular ability or strengths, hence the simple black and white colouring. The result is that it's incredibly versatile, able to literally absorb a "blueprint" of any ghosts he comes into contact with and integrates it into its own, effectively copying an enemy's powers. Take particular note of how he acquired ice powers after encountering Frostbite, learned how to "overshadow" people in the same episode that a possession-happy Artifact of Doom appears, becomes more and more proficient with duplication the more times he fights Plasmius, and after his absurdly powerful future self wipes the floor with him he picks up the equally powerful Ghostly Wail. And don't forget the central plot of "Torrent of Terror" where he absorbs weather empathy powers after a battle with a weather controlling ghost; the lightning Vlad blames this on could have just accelerated the process.

Danny is immortal
Think about it. He's a living person who can turn into a ghost. When he dies he'll be a ghost ... who can turn into a living person.

Danny wants his secret identity to be discovered.
Come on, he even chooses a name for his secret identity that is phonetically nearly identical to his real name.
 * Coupled with the fact that his future self mocked everybody for not figuring it out.
 * Pretty much confirmed in "Frightmare" in which Danny dreams of a perfect world where he's the star quarterback, smart enough to ace all his tests, Sam's boyfriend, and no longer has to hide his superhero status.

Danny gained Split Personality Disorder along with his ghost powers
I'm not talking about the "two different entities" kind of split personality many people believe. I'm talking about a mental change in his personality with the acquisition of his ghost status. Danny's base personality is that of a shy, laid back, and other-wise typical "under the radar" teen, but it seems that throughout the series, his personality makes a change in the transition into a ghost. As Phantom, Danny becomes bold and much more fearless than he was shown to be before the accident, as he was shown to actually be afraid of ghosts before (despite being the son of ghost hunters). Add the fact that is is willing to mock and exchange witty banter, something you wouldn't expect from the normally placid Fenton. This would explain why the Ghost Catcher just split his personality rather than expunging "Phantom"(it split his lax, fun-loving nature from his bold, heroic nature), because Danny is not two people, but rather just one person with two different complexes. This could be due to the fact that when Danny transforms, nobody knows who he is and essentially gives him a clear slate to work upon (along with the fact that being a ghost pretty much exempts him from mortal worries such as fitting in, or even many mortal laws). So essentially, donning his spectral looks allows him to put on a sort of social mask.

Danny is a Space Ghost
It explains why he wants to be an astronaut. Also, he certainly isn't a Scary Ghost.

Danny is the guardian of the underworld.
Though he doesn't know it.

The first time the Ghost Portal worked, he was immediately zapped by it, turning him into a halfa. Since then, ghosts are appearing all over the place in Amity Park, and Danny has been capturing them and putting them in the Ghost Zone. These ghosts are ghosts that are escaped from the Ghost Zone, OR have died and haven't made their way to the afterlife yet.

When the Ghost Zone first became properly accessible to the mortal world, they took they closest person (who happened to be inside the portal at the time) and appointed them underworld guardian, with the task of keeping the dead in and the living out of the ghost zone, and shepherding deceased souls into the next life. He is straddling the line between the two worlds - half-dead, half-alive.

Vlad was a failed attempt to create a halfa guardian. And since the ghost portal that zapped him didn't work again anyway, they didn't need him to guard it, but he was left with his halfa powers.

If Vlad had been more patient about revealing his powers to Danny, he might have won him over.
Danny clearly really liked Vlad the first time they met, even letting him get away with the type of nicknames ("Little Badger") that would annoy any teenager. But it all went south when Vlad decided to capture him and reveal that they were both halfas during that same visit.

We also know that Danny is sometimes tempted to use his powers the wrong way, from the big obvious one of his evil future self, to petty spite in using them to get back at bullies, to really small things like going invisible to sneak into the movies.

If Vlad had just kept quiet about his ghost half, even though it would mean risking Danny ruining his plans for the reunion if he wasn't captive (a problem which could have been solved by sending him off on a task that didn't obviously scream "evil trap" once he walked into it, or by having a human-form duplicate stick to Danny's side like glue to "protect" him while he possessed Jack so Danny wouldn't have a chance to transform), and if he was careful to fly under Danny's radar during his ghostly misdeeds so he wouldn't build up any more dislike for "Plasmius", he could have nurtured that companionship with Danny and nudged him down the path of moral relativism as a friend, and with enough time put into it he could have eventually revealed his ghost half to Danny and have him be glad that the cool rich guy he's friends with is a half-ghost just like him and wants to team up with him.

Of course, this assumes that Vlad would either be just as bad at ever seriously injuring Jack without Danny actively keeping an eye out for him as he is when he is, or that he'd be able to remove Jack from the picture in a way Danny would never be able to trace back to him, because I don't think any amount of time would be enough to make Danny happily join up with someone who hurt his dad.

Vlad did not realize his ghost powers right away
The ecto-acne was shown to be detrimental to his powers and had to be cleared up before he could use them-hence, the time gap between 1982 (when the accident occurred) and 1986 (when he pulled his first bank heist) exists.

Vlad actually is Danny's father.
Obligatory theory in a story with this kind of relationship, but seriously... Vlad feels comfortable openly flirting with Maddie in "Bitter Reunions" and with inviting her and Danny to live with him in "Maternal Instinct." In an alternate timeline where Maddie didn't marry Jack, she married Vlad. It's revealed in "Prisoner of Love" that Jack and Maddie having fights that end with Maddie leaving the house for a few days has happened so frequently, Jazz has become completely jaded to it; indeed, she almost has a nervous breakdown when their dad doesn't take it all in stride this time. It's not out of the realm of possibility that Maddie stayed with Vlad, their third amigo from college, during one of these fights and something happened, but she convinced herself afterwards That Didn't Happen. Fortunately for her, Vlad, Jack, and Danny all have/had black hair and blue eyes. Vlad knows Danny is really his son, of course, which is the reason why he spared Danny Phantom after discovering his Secret Identity, why he often condescendingly calls Danny his son, and for the cryptic "You're more like me than you know" speeches. And who could forget his line in "Maternal Instincts": "Maddie, you must be exhausted -- carrying the weight of that mistake you made all those years ago."
 * The last line of this paragraph. I never saw it that way before. Fridge Brilliance anyone?
 * That makes the entire series seem somehow darker. It makes a ton of sense though!
 * Take into account hair and eye color Jack has black hair and brown eyes, Maddie has brown hair and violet eyes, Jazz a green eyed redhead, and Danny black hair and blue eyes the same as Vlad before the accident.
 * Jack has dark blue eyes. But you have a point; the shade of blue in Danny's eyes is closer to Vlad's than to Jack's.
 * Adding to this theory: What if Danny is really Vlad's son--thus making Danny's powers genetic? Perhaps Danny had latent superpowers all along, and the potal accident only activated them, saving his life.

Why Dani Phantom is a girl
~ Dani is female because when Vlad tried to clone Danny, part of their instability was due to a key factor of biology: the Y-chromosome. In genetics, all life forms have an x number of chromosome pairs. Each pair includes a DNA code: the first chromosome, X, contains the mother’s genes; the other chromosome, which may be X or Y, contains the father’s genetic traits. The key controlling variable involves incubation: cooler temperatures create Xs (females), and warmer temperatures create Ys (males).

Therefore: XX=female, XY=male.

Because the female sex has evolved to be more genetically balanced, females are more stable. Due to this, a being that was not only created from scratch (partially, anyway) through artificial means, but is supernatural as well, is bound to be biologically unstable. The Y-chromosome only increased instability. This is the main reason why Danielle was stronger and more human than the other clones.

The other reason is that females are more naturally resilient than males are.

Ranma, anyone??


 * Nitpick: XX and XY chromosomes are not sex determinants for all forms of life (although they are for all mammals, like humans). Incubation temperature has no effect on sex determination among genetically determined species (unless you count a possible, much-debated effect on sperm survivability), but is a determinant for reptiles.

Dani has Complete Androgen Insensitivity Syndrome
Genetically, she's got the XY chromosome that makes a human male in theory; due to a problem in fetal development, she ended up female in practice. Postulated in this fanfiction by Nylah.

Dani has some of Vlad's DNA, or at least he contributed...*ahem* Gametes in the genderbending process.
For a zygote (fetus) to be female, they need to have two X chromosomes in their DNA. However, Dani is a clone of Danny, so unless someone contributed their Gametes, Dani would be a guy, and what else than Vlad?
 * I always assumed it happened like Wolverine's teenaged female clone: The Y chromosome in the sample was damaged and kept corrupting the clones, so he just doubled the X. The Y would be Jack's DNA anyhow, so Vlad wasn't too broken up to see it go. Now, this is probably bullshit from a scientific perspective, but this is a cartoon. Come on.

Danny would have done a Face Heel Turn on his own, without the Nasty Burger explosion, if not for Clockwork's interference.
According to Clockwork, "[h]e turns evil because he's under pressure from some test"! Not the accidental deaths of his friends, not because he had his humanity ripped out, but because he was under pressure. If Clockwork had done nothing, the fight with Box Lunch would not have occurred, and thus Danny would not have the CAT answers in the first place (unless he took them himself, beginning his path of darkness). Because there was no fight, Danny would not have cheated (or would not have been caught, possibly), Mr. Lancer would not have called his parents, Sam and Tucker and Jazz would not have tried to stop them... and there would have been no explosion in the first place, since the accident was caused by Box Lunch and Danny's fight. Clockwork deliberately caused the most horrible future possible for Danny to scare him away from the Dark Side and manipulate him into making his promise to never turn evil, after he'd seen what his Face Heel Turn could do. In the words of the Observants themselves, Clockwork "manipulated the boy [and] influenced his choice!"

In other words, there were three time lines we know had/could have happened: One--the original time line-- in which Danny became evil on his own, one in which he became evil and lost his family because of the explosion at the Nasty Burger, and one in which Danny witnessed the second time line and was frightened away from becoming evil.
 * Or maybe just the second and third. Clockwork may have taken Dark Danny and Box Lunch from a parallel timeline just to teach Danny a lesson. He even calls time a parade, and who's to say that there can't be multiple parades occurring at once in separate locations? This would also explain why Dark Danny exists outside of time, since he's originally from outside the timeline we see on the show.

Clockwork created Dark Danny, and we never saw an "original" timeline
We are invited to think that the future in which Danny becomes evil is the "organic" timeline -- what would have happened if nothing interfered with the course of history. We are also invited to think, as Danny does, that Clockwork's intervention was for Danny's benefit.

This may be. But what if Clockwork didn't just want a timeline where Danny never turned evil at all, but a timeline where a good Danny had crossed paths with an evil Danny? Might that have required tampering with the timestream to create a specific Bad Future where Danny did go bad? What if Clockwork intentionally created Dark Danny's timeline -- meaning the "original", unaltered timeline was something we never saw?

We don't have hard evidence for it, but there are some clues that could point to "Dark Danny's" future not being the original. For one, there's the Temporal Paradox with Box Lunch, who comes from a future that necessitated her interference in the past. If not for Box Lunch, Danny wouldn't have inadvertently acquired the test answers, and the Nasty Burger would not have blown up. This works if you're operating under a Stable Time Loop, but since we are emphatically not dealing with a future resistant to change, this means there is no natural confirmed sequence of events that leads to the rise of evil Danny. The other potential clue is Dark Danny's remark that Clockwork is "meddling again" - Dark Danny already knowing about Clockwork and thinking he's a meddler, hints that Clockwork has indeed "meddled" with Dark Danny's own timeline, which is very curious if his is supposed to be the original.

(Mind you I'm aware that both of these could be rationalized. Maybe Box Lunch just replaced the original sequence of events. Maybe Dark Danny had crossed paths with Clockwork elsewhere for some other unrelated issue. It's just something to consider.)

So why might Clockwork have done this? Well, Danny did learn a few lessons on his trip to the future. His encounter with a repentant Vlad, after having been confronted with the evil in his own soul, led him to conclude that maybe all anyone needs is a second chance. He learned... well, the Anvilicious nature of the lesson about cheating has been mocked elsewhere, but obviously there was that too. He even physically picked up something in the form of his Ghostly Wail, something Dark Danny didn't pick up until he was 24. Without the Ghostly Wail, 14-year-old Danny may have died on occasion, and without Danny alive some other catastrophic event may have gone unchecked.

Most intriguingly, though, the result of "The Ultimate Enemy" is that a Dark Danny exists despite the evident nullification of his origin timeline, and he exists in Clockwork's custody. The Observants seem to think that's a punishment (for Clockwork). I'm not at all sure Clockwork's remark that "everything's the way it's supposed to be," means that HE sees it that way.


 * On the subject of Dark Danny, one possible interpretation of him being in Clockwork's custody is that CW now has an extremely powerful ghost at his beck and call as seen in Grim Tales From Down Below. Now wonder he's content with the way things have turned out.

Clockwork is a villain.
He didn't change things in "The Ultimate Enemy" to stop Danny from becoming evil; he ensured he would. Like Dark Danny said, "I'm still here! I still exist! That means you still turn into me!" Albeit under different circumstances. Somewhere down the road of the surviving timeline, Danny still turns evil thanks to Clockwork meddling with the timestream: "His future is sealed."
 * He ensured all that would happen because he knew of the need of Justice paladin to fight where he wouldn't be able to meddle, and showed Danny the darkest future possible to keep him from turning evil and keep him in a more good way, as said lower on the page.
 * Dark Danny still existed because before that timeline was erased one of Clockworks medallions was phased into Young Danny permanently putting him and ALL of his possible future selves outside of time so as long as they aren't there when a timeline is destroy they can still exist. (They wouldn't exist in a timeline that was erased because there would be nothing there so by default they are destroyed.

Clockwork caused Vlad's accident to balance out Danny.
Danny's struggle with darkness is one of his major arcs, and Vlad is usually there to not just egg him on, but to show a visual example of the type of person he can become. Vlad is there so Danny has something to look at and remind himself he's on the good side so in return he doesn't go around destroying the world; without Vlad, there's a good chance there won't be anyone powerful enough to stop him.
 * Or, because of Vlad's constant scheming (theft, overshadowing blue chip company owners, etc.) and his plans to kill Jack, perhaps it was the other way around and Clockwork caused Danny to get his powers to have someone to oppose Vlad.

Dark Danny is Danny's Heartless.
In essentials. Bad Future Vlad did say he "removed all those painful human emotions." That's just what he did: he removed all the hate, pain and anguish from Danny. The result was Ghost!Danny with all of Danny's negative emotions, hence why Dark Danny is an Axe Crazy Complete Monster.
 * No, that would make him an Unversed.

Dark Danny was created by accident.
When Vlad removed Danny's ghost self from his human self, the ghost self (which may be the overly heroic version from "Splitting Images") decided (or had already planned before coming to Vlad) to stop the Big Bad by separating him from his ghost half. Danny believed that he could merge with and overpower Vlad's ghost half (much like how Neo destroyed Agent Smith's body in The Matrix) but Vlad's ghost half overpowered him, creating Dark Danny. So Danny's ghost half was never the painful emotions Vlad said he'd take away but a separate, noncorporeal conciousness.

Clockwork was one of the ghosts that sealed Pariah Dark the first time.
He's certainly been around for a while and is quite powerful. Several fans noted the similarities between Clockwork's hooded robe, and the hooded robes worn by the five [Was it five? it's been a while] ghosts in the flashback to the initial sealing of Pariah.

Skulker's suit is partly organic
Remember in Life Lessons when Skulker got shot by all those darts? Even though his suit is supposedly just a shell, he still became paralyzed. It could be that he built the suit so he could fuse with it organically, so he could continue to have his senses in his bigger form. That would also explain how he could "feast upon" another ghost, as he claimed he would that same episode. This could also explain how he gets Ember as a girlfriend. She strikes me as the kind of girl who wouldn't stick around if a relationship wasn't physical, and this is accomplished because even those parts of him are enhanced by the suit.
 * That or his suit is just one giant, anatomically correct sex toy for Ember.
 * Maybe he's overshadowing his suit? It's strongly suggested that Technus does this, considering how the Fenton ghostcatcher can stop him from using part of a machine.
 * It's possible his suit is organic, but if you listened to Ember, it didn't seem like she cared much for their relationship in the first place. And judging by how well her normal life's relationship went, I don't think she'd care for a sexual relationship. No, I think his suit is organic for the dart reason, plus Skulker actually seems to feel the pain when he gets hit...unless he just gets knocked around in that suit of his.

Spectra was a witch (and alive) in her debut
Something that always bugged me was that she resembles a witch in her first appearance more than she does a ghost; she has a familiar, and has to drain lifeforce to keep herself young (which would make no sense if she was already dead.) Her ghost form also does not resemble the others.In the end of the episode, she is reduced to an old hag. Yet, in later episodes, she resembles the other ghosts. In other words, she died off-screen, and became a ghost.
 * Maybe she’s a witch with ghost-based powers.

Ghost-Ember isn't the real Ember.
A stalker with a crush killed the real Ember and then herself. The song isn't being sung by Ember to the crowd, it's being sung by the stalker to Ember, perhaps in remorse.

Watch the following video (with annotations on) while thinking about it from this perspective and see what you think: http://www.youtube.com/watch?v=oWNS5HLzu4A&feature=related


 * Oh… wow. Just… eeeeeeek…

Johnny 13 and Kitty are bonded together for eternity.
It's a ghost thing--maybe they died together, maybe one died and waited a while for the other to join them as a ghost in the afterlife, who knows? But the two of them never are able to break up for long--their ghostly obsession is each other. A couple of Johnny's lines from "13" made me suspect this: "Johnny:I'm trying to find the right girl for [Kitty] to take over. I mean, if I've gotta look at her face for all eternity, I wanna make sure I like it, dig?

Johnny: What can I say, doll? No matter how hard I try, I can't stay away."


 * Also, look closely at Johnny's hands in "Girls' Night Out"--a gold ring on his left ring finger!

Sydney Poindexter wasn't the only one who died within the school.
Seeing as Sydney was pretty much stuck inside of 1950's Casper High (despite in later episodes, where he's made minor appearances), every one of his peers had joined him. The story hints that Poindexter might have died in his locker, which makes sense. However, what about the other students? I highly doubt they were shoved into lockers as well. The only explanation could be is that they died around the same time as him. An accident might have occurred at the school, say, a noxious gas, fire, or an internal explosion that caused the entire student body to die, and therefore, a replica of the structure was formed inside of the Ghost Zone, and the soul of every student went along with it (via Sydney's locker mirror). Poor teens, they probably never knew what hit them.

Could they be Gods?
Around Season Three (with some exception in other seasons), the ghostly villains arguably got bigger and grander in terms of power and scope. Danny now battles ghosts that represent something or another: Ghosts of weather, plants, time, nightmare, dreams, etc. Their level of powers seem to exceed somewhere beyond what most of the ghosts of Season One and Two possess. Could they actually be Gods? Could they be deities that were told in forms of legends and myths over time? Or could they be the Ancients that defeated Pariah Dark in Skulker's tale in "Reign Storm"?
 * If that's the case, then Nocturne had gone by many names, including the Sandman and Morpheus (the Greek God of Sleep).
 * Could he be that Sandman?
 * Alternate: In-show, the gods of various folklore were actually ghosts that escaped the Ghost Zone (through natural portals). We've already seen Medusa, Pandora, a Cyclops, a Centaur... need I go on? As Vlad said, "Funny, all I had to do was float a little bit and these Romans hailed me as a deity."
 * Clock Work is the god of time.

How they became ghosts, and why they are ghosts
Related to the theories on what the ghosts were and how they died, the reason most of the ghosts are villains are because something in the process of dying and turning into ghosts caused them to go insane, wrapping their whole personality around some aspect of their lives before they died. Maybe the people who became ghost are those who couldn't accept their fate. I mean, not every person who dies turns into a ghost. Possibly, their refusal to accept that they are dead has manifested partially in a rage against the human world. And most of the "good" ghosts don't seem like they ever lived in the human world.
 * Or the Ghost Zone is actually Purgatory. And the ghosts?
 * The Box Ghost was a simple menial worker who no-one cared about. He's pissed that his life meant nothing, and wants to make meaning as a ghost criminal. He died in a box-related incident.
 * The Lunch Lady used to be, well, a lunch lady. However, her food ended up being tainted. Dedicated to her work, she refused to believe this, and tried to prove them otherwise. It didn't work out.
 * Skulker was a bounty hunter wanted by countless governments. The reason why he's a puny little ghost was because he was an Evil Cripple.
 * Technus was just like what we was in life. He died in some crazy experiment.
 * Walker was a corrupt chief during the 1920s, shot down by the mob.
 * Penelope Spectra was in charge of age-reducing cream, and other cosmetics. She died at the grand old age of 100.
 * Ember Mc Clain was a popular singer, however suffered from depression. Unknown to anybody, she killed herself.
 * Youngblood was the son of a pirate.
 * Johnny 13 and Kitten were a teenage couple who died in a drunk car crash
 * Pariah Dark is Genghis Khan.

What Being Half-Ghost Really Means
Throughout the series, it is repeatedly mentioned that Vlad, Danny, and Dani are half-human, half-ghost. Episode 5, “Splitting Images” even coined a term for this: halfa (as in “half-a human, half-a ghost”). Although the term itself is only mentioned in one episode, the rest of the series often refers to it, using terms like “half-ghost”, “part-ghost”, and even “half-ghost hybrid”.

When Danny went inside the portal to the Ghost Zone, he accidentally activated it while inside. This caused him to be electrocuted and mutated with ectoplasm(1). Whiling enduring said shock, he was caught between two worlds… and two different states of being.

One factor that makes a half-ghost is mutation. A halfa's body is altered to have the potential to use ghost powers, but it also needs fuel. What makes Danny half-ghost is the fact that when he activated the portal, ecto-energy(2) directly from the Ghost Zone fused with his molecules… and his DNA, changing him permanently. As long as the ectoplasm in his blood is active, he’ll always have his powers. The various times Danny temporally lost his powers caused the ectoplasm to retreat, going dormant. This mutes his ecto-signature(3), and blocks off his ghost half. Without the ecto-energy in his ghost half, his body was like a car without gas: it had the potential ability, but no fuel.(4) When Danny manages to split his human and ghost halves apart, they become separate entities but are part of the same persona. If one ceased to exist, the other would die as well.

The other, much darker factor of being half-ghost is this: being half-dead.

As Danny's biological make-up was being altered, he had already begun to die. But halfway through the process, there was enough ecto-energy in him that it froze him in a state between life and death. In order to balance out, he was given two forms: one that was more human and one that was more ghost. He keeps most of his powers as a human, but can use them more easily in his ghost form.

If an attempt to fully remove his ghost half was made, he would die. Permanently.


 * (1) Ectoplasm: the physical substance used by extra-dimensional beings to manifest themselves on this plane of existence; basically ghost-matter.
 * (2)Ecto-energy: the source of a ghost’s abilities.
 * See: Ki Attacks, Cold Flames
 * (3) Ecto-signature: the unique wavelengths that all ghosts emanate; somewhat similar to the genetic codes in DNA that make all life forms unique. The source of these wavelengths is in the ghost’s core, and contains all the information that the ghost itself is made up of. Ecto-signatures can also be divided, making duplication possible. Duplication isn't just cloning; it splits the ghost's core, making 2 copies with half the ghost's original power. The downside is that it also divides the ghost’s energy.
 * See: Our Ghosts Are Different
 * (4) One of Darth Frodo's theories.
 * (5) More commonly known as "Dark Danny" and "Dan Phantom"
 * Came Back Strong
 * Did You Die?: could be.
 * Half-Human Hybrid
 * Inhuman Human
 * It Is Not Your Time: theoretically.
 * Near-Death Experience: very.
 * Not Quite Dead: related.
 * Only Mostly Dead: related.
 * Please Wake Up

The Ghosts are dead demi-gods.
It would make sence going by the ghosts individual powers, why there are so few ghosts in the Ghost zone, and why characters from greek mythology show up (Pandora, Madusa, Argus) • Ember Mclain, daughter of Apollo • Teachnus, son of Hephestus • Undergrowth, son of Demeter • Clockwork, son of Kronos

Ghosts are the manifestation of a person's darkest thoughts and feeling when they were alive.
Which is why so many of them are antagonistic. Ember might have been a pop star who feels bitter that she didn't become very famous in life ("Ember, you will remember my name."). Box Ghost was a downtrodden, lower middle class worker who felt he was wasting his life in his mediocre job, and felt like he meant nothing to society.

Some of these ghosts managed to hold onto their nicer thoughts and feeling, such as the Dairy King, which is why they're at least decent people. Some of the ghosts were never living at all - e.g. Clockwork, Pariah Dark, Nocturne, etc. - which is why they are physically different, have different powers, and act differently.

Danny Phantom is more confrontational than Fenton, and when Danny is angry his eyes flash green.

Vlad and Danny had different side effects from the ghost portals because of the power difference.
The supposed incompleteness of the original, miniature portal wasn't an issue; the portals had the same sort of radiation. The difference is that Vlad got spillover radiation to the face, burning his skin with ecto-energy that slowly changed his body over the next few years, and Danny was standing inside a portal, which infused his body immediately (and may have semi-killed him in the process). If half-ghosts half-died to get their ghost powers, as has been postulated before, Vlad may have "died" a slow death of ghost-radiation poisoning (the ecto-acne) while Danny "died" almost instantly.


 * This makes so much sense. I salute you, fellow troper.

Ghosts are ideas.
You'd likely get this theory best if you read Diskworld but the basic concept is ghosts are manafestations of peoples beliefs.
 * Ghosts of dead people are a combination of how they saw themselves and how everybody else sees them but not the actual person.
 * Nature spirit type ghosts are the result of people personifying nature.
 * Jhonny's shadow is the result of people thinking bad luck follows him.

Butch Hartman is a Harry Potter fan.
The most obvious hint is Vlad, who seems to be an Expy of both Voldemort in his mannerisms and lust for power, and Snape in his love for Danny's mother and his hatred of his father. Further, Danny's superficial crush on Paulina is like Harry's time with Cho Chang; Doomed. Also, the entire plot of one episode revolved around Tucker's jealousy driving him to an antagonistic role for a while before seeing sense, much like the Locket's possession of Ron in Deathly Hallows. Finally, Danny and Sam's relationship can be compared to that of Harry and Ginny at times. There are also hints of this in his other works.
 * A lot of this makes sense; however, the episode What You Want (where Tucker gets ghost powers) came out in 2004, whereas Deathly Hallows wasn't published until 2007.
 * J.K. Rowling is a Butch Hartman fan
 * Harry Potter himself (or, at least, someone dressed as him) made a cameo appearance in the crowd of comic book nerds in "Reality Trip".

Poindexter thought Danny was Vlad when he first met him
Vlad's also a "halfa" and probably had more impact on the Ghost Zone then Danny did at the time. Poindexter hadn't seen either of them before and only heard stories about how he's half human-half ghost. Danny fit that definition.
 * WHOA. That actually explains a LOT. Cool.
 * Poindexter says that the ghosts spread rumors of someone who was "half a boy, half a ghost". I can't see anyone referring to Vlad as a boy, rather than a man.

D-Stabilized chronologically takes place a lot earlier than when it aired in relation to other episodes.
Aside from being the only episode in Season 3 that's any good, Vlad is his old characteristic manipulative, pre-Villain Decay self still obsessed with Danny. Not as much time as the entirety of Season 3 could have passed after Valerie upgraded her suit and gear if she works for Vlad so often he has a button in his office to summon her but he hasn't seen it yet. This would also explain Valerie's absence in the rest of Season 3, since she quit working for Vlad after discovering his Secret Identity.

Tucker, Paulina, and Dash all have ghosts (of themselves) in the Ghost Zone.
In "What You Want," Desiree blasts them with "ecto-energy." This ectoplasm binds to the kids and takes on their characteristics and personalities, multiplying it in the typical manner of ghostly obsessions. Danny eventually removes the kids' ghosts in the same way he does for overshadowing ghosts: he blasts them out, then throws them in the Ghost Zone. Presumably, they're still there. Somewhere, Tucker Phantom is wandering the Ghost Zone, having become the embodiment of Tucker's jealousy; somewhere, a Sayonara-Paulina is jumping around with the joy of (after)living; and somewhere, there's still a Dash monster terrorizing the Zone.
 * If the series had continued they would have joined together under Desiree to form a team of ghostly opponents for Team Phantom. Danny and Sam would have loved trashing the Dash and Paulina ghosts respectively.

Sam is Danny's real sister, Jazz is the real cellophane-deli-toothpick-twirling-heiress, and no one knows, knew, or ever will know about it.

 * Yeah, I know, totally insane and makes the end of PP somewhat unnerving, but hear me out. Look at Sam's eyes. Look at her parents'. Now look at MADDIE'S eyes. Now look at Jazz's. Now Jack's.
 * Sam: Lavender/Purple, no irises.
 * Maddie: Purple, irises.
 * Sam's parents: Green(Mom) and Blue(Dad) both have irises.
 * Jazz's: Same green shade as Sam's mom, and irises.
 * Jack's: Blue, no irises.
 * I, the original poster, don't know about you, but from that and hair colors, I can draw a pretty good Ass Pull of a defense for this. With these details, I submit to you, Tropers of the world and Phantom Phans alike, that Jazz and Sam were swapped at birth. Sam seems to be more intelligent than anyone else in that grade, so maybe she and Jazz were born on nearby dates, and someone in the hospital fucked up and switched their nametags (or whatever is used to ID newborns). Sam's lighter, lavender shade of purple could be a diluted form of Maddie's deep purple via Jack's icy-blue, and Sam also get's Jack's lack of irises. Both Sam's parents have irises, and Jazz has the exact same eye color as Sam's mom with irises. Sam's mom also is a vibrant-colored redhead, like Jazz. Maddie's a brunette, which thanks to Jack's black hair let's her have Danny and Sam who both have black hair. To make this work with Sam being in Danny's and Tucker's grade, Sam gets held back 2 years in Preschool, K, or 1st grade because of her independence and violent tendencies, and meets Danny and Tucker in 2nd grade before the Ricky Marsh incident. This also explains Jazz being as peppy as Sam's parents early-on, while Sam went Goth because on some subconscious level, she knows but doesn't know she knows that these crazy people she's grown up with are not really her parents.
 * Keep in mind that red hair and violet eyes are recessive. If you assume that Maddie and Jack each have a red hair gene that's overridden by their brown and black hair genes, then every child they have has a 25% chance of getting two red hair genes, resulting in Jazz's hair color. Likewise, Sam's parents could have recessive violet eye genes. The only anomaly here is Sam's black hair, as the black hair gene would have overridden the blond and red hair of her parents, but it's not unlikely that she dyed it to match her Goth appearance (One of her parents could have dyed their hair as well, but that's less likely as they have less visible reason to do so).
 * ...Sam's age is never stated in canon, is it?
 * I have all 53 episodes (26 1/2 hours) downloaded. I watched them all over the weekend back-to-back. I never heard any ages stated, even relatively to another, besides Danny (14) and Jazz (2 + Danny = 16). Inference from the timeline can tell us that the College Trio are all at least 40. But no mention on Sam. This is getting way too plausible for comfort...
 * In "Masters of All Time", Sam mentioned something about not being able to have a 15th birthday. She might have referred to Tucker, though.
 * Semi-OT: Paulina turned 15 in Memory Blank.

Amity Park is in Michigan.
The town is near the water and about a day's drive from Wisconsin and Lake Erie, which is spelled with two e's in the Danny Phantom-universe. Makes sense to me (might not even be a Wild Mass Guess).
 * Actually, I've asked David Kaufman where it is (because Butch Hartman never answers his fans on Facebook) and he said either Minnesota or Wisconsin.
 * Amity Park can't be in Wisconsin because in "Secret Weapons" Jack recognises the area code of an out of state number knowing the area code from when he went to collage and the only person he knows in Wisconsin is Vlad means that Amity can't be in Wisconsin.
 * There's a visible palm tree at the end of "Identity Crisis" and they cross a desert to get to Vlad's in "Bitter Reunions". Amity Park is probably in California.

Clockwork is preventing Danny's enemies from revealing his identity.
If the ghosts had really wanted to make Danny's life hell, they could have revealed his Secret Identity early when the entire town hated him ("Public Enemies," for example). Why didn't they? Clockwork. The Ghost Master of Time made it clear that blowing Danny's cover would be... unwise. If a guy who can wipe you from the timeline tells you not to do something, you can bet even the surliest ghost won't try it. He did, however, encourage them to challenge Danny to increase his skills and moral fortitude for whatever plans he has for Danny.

If Jack DID have a "clever quip" in Boxed Up Fury, it would've been...
"ALL WORK AND NO PLAY MAKES JACK A DULL BOY!" *shoots gun*

Sam's parrents do support her veiws and pay the school to do what she likes.
Remember "Mystery Meat" most if not all schools by law must have a vegetarian alternative what other school whould change the school lunch menu entirly to, well dirt on bread yes the teachers have the all-steak buffet but also in "Idenity Crisis" Sam steals all the frogs from the science lab and get away with it buy making some popular freshmen agree with her. No schoolboard would let a child act like that normaly but if that very board is being paid off.
 * They might support her extreme activist but they clearly don't support her being a goth. They could either genuinly support her activist views or see it as the lesser of two evils and support it hoping it will distract her from being a goth.

The show occurs in the future of Ghostbusters.
Ghosts have changed over time as their presence waxes and wanes, causing disbelief to rise again before the start of the series. The Fentons are old fans of the Ghostbusters and have improved their technology. It would have been awesome to see the old Ghostbusters crew as a team of Retired Badasses anyway.
 * Perhaps on the future of Filmation's Ghostbusters, even. Ghost catching rope, ectoplasm gum, it makes sense.
 * Ghostbusters The Game makes this even more plausible, with a short romp into an unnamed ghost dimension in 1991, possibly the first human contact with the Ghost Zone. Ghostbusters' ghost dimension is a parallel of the human geography, however, this doesn't make it incompatible- Note how easily Ember, Skulker, The Box Ghost, and others find new homes in Reign Storm, perhaps these are the places exaggerated into their lairs in the Ghost Zone?

Skulker is the ghost of a Predator
Probably the one in either of the movies. Predator ghosts are different.

The show takes place in the same universe as Teen Titans.
Slade and Vlad Masters use the same technology, namely nanotechnology designed to kill someone from within their bloodstream, in "Apprentice" and "Secret Weapons." Slade probably stole it from Axion Labs or worked for them at some point.
 * Strange theory considering that one of the voice actors, Ron Perlman, plays Slade who is the sadistic villain of Teen Titans while also playing Mr. Lancer in Danny Phantom who... well, reminds this troper of her Biology teacher.
 * Also, Raven’s voice actor, Tara Strong, plays both Ember McLain and Star.
 * BTW: She also voices Timmy Turner.
 * OR they are set in different dimensions, and the Ghost Zone and Human Zone (??? whatever they call it) aren't the only zones out there. Somewhere, there are natural portals between the TT and DP world.
 * ...You mean Earth?

The Soul Society and Hueco Mundo are sub-sections of the Ghost Zone.
Just ones that focus more on Japan then the rest of the world, the gates that the Soul Reapers and Arrancars use to travel to the world of the living are really ghost portals.
 * To continue that theory...

The Ghost zone is a part of the Nevernever
Considering that most of the afterlives are said to be somewhere in the Nevernever, it makes sense that it would be possible that the ghost zone is just a part of it.

Dash Baxter has a job as an actor on his weekends.
The actual character, face and voice, showed up on The Fairly Odd Parents as an actor in a movie relating to flys. The movie was a spoof on teen wolf.

Ember Mc Lain is a Vocaloid.
Specifically, she is the future of Hatsune Miku. Occured to me after watching this video - I just kept thinking about how the way she looks here reminds me of Ember.

Miku will eventually become self-aware enough to be rebellious and break away from her creators, becoming angry in the process (and getting a bunch of tattoos). Unfortunately, spending years as pretty much the face of Vocaloid and under a huge spotlight turned her into a major attention whore - so much so that it's embedded into her programming that she is dependant upon popularity. She will now do anything to be popular, including mind control.
 * This. Is. Awesome.


 * Note how she bursts into blue flames in this video to transition to different outfits between songs.

Ember Mc Lain is Azula.
1. They have a "blue fire" motif. 2. They have the same hairstyle. (Well, Ember has a ponytail and Azula has the Fire Nation topknot. But they have the same bangs.) 3. They both want to rule the world. 4. They both receive a Significant Haircut. (Ember gets hers at the end of "Fanning the Flames," and Azula gets hers ) 5. They are both good at manipulating people. (Now, this troper hasn't seen all of Danny Phantom, so if there are any details that Joss this, she doesn't know about them yet.)