Ace of Spades (fanfic)

Ace of Spades by Leontina Stardust is a Batman: The Dark Knight and Harry Potter Crossover and Slash Fic (The Joker/Harry Potter, Poison Ivy/Harley Quinn).

After saving the world Harry gets PTSD and loses control of his magic,  The Magical World, not wanting to get their hands dirty with charging their world's savior quietly strips Harry of his wand and has him secretly sent to a Muggle Asylum. Forsaken by the very people he saved Harry is shuffled between various mental institutions; none of which are prepared to help a wizard and Harry's condition worsens into full on psychosis. Harry ends up in Arkham where he makes the acquaintence of a mad doctor with a burlap sack over his head that wants to use him in his experiments, a police officer that is actually concerned about his well-being, and a fascinating man with scars on his face who who also wants to see the world burn...

(Has nothing to do with the video game of the same name.)

Ace of Spades provides examples of:

 * Accidental Murder:
 * Affably Evil: Harry and his new "friends."
 * Attempted Rape:
 * Axe Crazy: The Joker and Harry.
 * Bastard Boyfriend: The Joker to Harry.
 * Because You Were Nice to Me: This is part of the reason why Harry becomes obsessed with Jim Gordon.
 * Bedlam House: Arkham Asylum
 * Being Tortured Makes You Evil
 * Big Sister Mentor: Harley Quinn to Harry.
 * Broken Ace: Harry as the Ace.
 * The Chessmaster: The Joker, Harry is an aspiring one as well.
 * The Commissioner Gordon
 * Composite Character: This Joker is a fusion of the Heath Ledger and Jack Nicholson versions.
 * The Corrupter: The Joker.
 * Crazy Jealous Guy: The Joker is jealous of the time Harry spends with Bruce Wayne and of the attention Harry gives to stalking Jim Gordon.
 * Cute and Psycho: Harry and Harley Quinn
 * Dark and Troubled Past: Harry.
 * Dark Fic
 * Death Dealer: Harry as Ace.
 * Discard and Draw:
 * Dragon-in-Chief: Harry Potter / the Ace of Spades is much more powerful than the Joker but the Joker makes it clear who's in charge.
 * Driven to Madness: Harry.
 * Dude, Where's My Reward?: After saving their world, the magical world has Harry Potter committed.
 * Et Tu, Brute?: Harry feels very betrayed when Ron and Hermione testified against him.
 * Evil Is One Big Happy Family: there are many cameos of other members of Batman’s Rogues Gallery.
 * Evil Makeover: Harry as the Ace of Spades.
 * Evil Mentor: The Joker.
 * Fallen Hero: Harry.
 * The Family That Slays Together: The Joker, Harry, Ivy, and Harley. Joker is like the daddy, Ivy is like the mommy and Harry and Harley are like the bratty kids. "It's my turn to fire the bazooka!"
 * Fan Art: and
 * Five-Bad Band:
 * The Big Bad: The Joker
 * The Dragon: Harry Potter,
 * The Evil Genius: Poison Ivy
 * The Dark Chick: Harley Quinn and
 * Fusion Fic: The fic loosely follows the plot of The Dark Knight and Harry seems to have taken the place of Two-Face in the narrative. (The Fallen Hero that is corrupted by the Joker and has ties to Bruce Wayne and Jim Gordon.
 * Genki Girl: Harley Quinn.
 * Go Among Mad People
 * Hero Antagonist: Batman
 * Hypercompetent Sidekick: Harry/the Ace to the Joker.
 * I Reject Your Reality: Harry has become delusional believing that Sirius must
 * Knife Nut: The Joker and Harry.
 * Knight Templar: The wizarding world and their attempt to "help" Harry.
 * Living With the Villain: Harry befriends Bruce Wayne; neither realize the other's true identity.
 * Manipulative Bastard: The Joker towards Harry  Also Harry plays   and Bruce Wayne like a piano.
 * The Mentally Disturbed: Harry and his new friends.
 * Mind Rape: It's what Scarecrow does for a living.
 * Never My Fault: It's not Harry’s fault he  It's all THEIR fault.
 * Parental Substitute: Poison Ivy reminds Harry of his mother and
 * Patchwork Fic: The fic is based loosely on the Nolan-verse but it also incorporates elements from the earlier Batman movies as well as the Batman comics and animated series.
 * Playing With Fire:
 * Power Incontinence: Harry becomes so stressed he loses control of his magic.
 * Protagonist Journey to Villain: Harry.
 * Psycho Ex Girlfriend: Averted. Harley Quinn is psycho and the Joker's ex-girlfriend but she’s moved on and bears no animosity towards the Joker or Harry.
 * Psycho Psychologist: Dr. Crane/Scarecrow.
 * Psychopathic Manchild: Harry.
 * Sanity Has Advantages: Harry is THIS close to discovering that Bruce Wayne is Batman but instead he gets distracted by some pretty rollerskates.
 * Scars Are Forever: Of course Harry already has the one scar but the Joker gives him some more.
 * Self Harm: And Harry gives himself some more scars.
 * Shell-Shocked Veteran: Harry and It Got Worse from there.
 * Slash Fic: Joker/Harry and Ivy/Harley
 * Social Engineering: Harry is a master at it.
 * The Sociopath: The Joker, Insane!Harry, the Scarecrow, Harley, Ivy.
 * Stalker Without a Crush: Harry towards Jim Gordon after Harry
 * Superpower Lottery: Even when depowered and suffering from Power Incontinence Harry is still one of the most powerful characters in the setting he's in.
 * That Man Is Dead: Harry Potter is dead. There is only Ace.
 * Title Drop: Harry's new villain name is Ace of Spades.
 * Too Funny to Be Evil
 * Transplant: Harry Potter and  in the Dark Knight Trilogy.
 * Troubled but Cute: Harry
 * Unreliable Narrator: Harry is nuts so his perceptions are a bit skewed.
 * Unwitting Pawn: Harry to whatever the Joker has "not" planned. Harry wants to burn the world down but it's also pretty clear he's being deceived...
 * Villain Protagonist: Harry.
 * Villain Team-Up
 * Wholesome Crossdresser: After escaping Arkham Harry is eager to get out of the straight-jacket even if it means wearing Harley's clothes.
 * Woobie, Destroyer of Worlds: Harry as Ace.
 * You Have Outlived Your Usefulness:
 * You Look Familiar: Harry upon meeting Jim Gordon because Jim Gordon and Sirius Black are both played by the same guy.
 * You Wouldn't Believe Me If I Told You: If Harry told his doctors anything approaching the truth, they would only assume he was more delusional.
 * Yuri Genre: Harley and Ivy are the Beta Couple.