Couldn't Find a Pen



"Kryten: The poor devil scrawled it in his death throes, using a combination of his own blood and even some lengths of his own intestines. Rimmer: Who would do that? Lister: Someone who badly needed a pen."

- Red Dwarf, "Psirens"

Maybe pen and paper weren't available. Maybe that just wouldn't be cool/creepy/dramatic/funny enough. This is a trope for writing with unusual equipment.

A particularly common (and gruesome) version is a victim of a murder or monster attack to use the last of their blood and strength to write a Dying Clue. Also the blood will often be immune to oxidization, remaining bright red no matter how long.

See Also: Distress Call, Room Full of Crazy and Deal with the Devil; all of which use or overlap with this trope to some extent. There may be Bloody Handprints nearby as well.

Anime and Manga

 * In Naruto:
 * In the final episode of Death Note, after This is actually a pretty severe "What the hell were you thinking" moment, as apparently at this point he had lost all self-control whatsoever and couldn't just calmly write down the name. Also, that's how he managed to write the third Kira's name without being noticed while in the helicopter with L.
 * While investigating the Mariage case in StrikerS Sound Stage X of Magical Girl Lyrical Nanoha, one of the things found was an ancient Belka psalm painted in blood over an entire wall.
 * Parodied by Sayo's chapter in Mahou Sensei Negima. Trying to calm down the panicking class after they mistook her for a malevolent ghost, Sayo wrote "It's a misunderstanding" on a window. Unfotunately, since being a ghost, the only writing material she had was blood, and "It's a misunderstanding" in katakana is the same as "Death five times", all it did was make the class panic more.
 * In Princess Tutu, Drosselmeyer is said to have written a story in his own blood
 * Parodied in one of the Omake strips in the back of one of the Fullmetal Alchemist volumes—Roy reveals that he wants to make all the women in the military wear tiny miniskirts, but then also admits that he'd fire all of the men at the same time, which prompts them to shoot him. His last words are written in his blood on the floor next to him: "Miniski..."
 * Lest we forget, Al's blood seal? The iron in the blood made it possible to bind his soul to the armor, so even if Ed could have found a ballpoint while flailing around in a sea of his own blood, it wouldn't have worked quite as well...
 * Also the scene where, after losing his gloves and the runes inscribed on them, Roy carves his alchemical runes into his own skin.
 * Bleach uses an instance that plays this trope every way simultaneously except for straight. Urahara tells Ichigo to leave his window open on the night that they leave for Soul Society, and on that night, he sends a balloon through the window, which splatters over Ichigo's wall. The liquid in the ball (which looks alarmingly like blood to Ichigo) drips down and forms a message. After the important bit of the message has been formed, it keeps on going to form a post-script: "Anyone who thinks this looks like the message of a dying man has no sense of humor."
 * Not even five minutes later, Ichigo runs into Chad and Orihime, who mutter about the fact that "apparently [they] have no sense of humor," leaving Ichigo to think "So they got that message too..."
 * Happens all the time to victims in Detective Conan.
 * Parodied in Soul Eater. During an episode involving the entire cast taking a test, Black* Star gets caught trying to steal the answers. The teacher beats the crap out of him and hangs him on the board as a warning. Later, when Soul is getting very desperate (having had his cheat sheets taken away), he sees Black* Star writing on the board in his own blood. Cue melodramatic inner monologue about how he must be trying to save his friend in dire straits- until Soul realizes it's an autograph. He is not amused. The audience is.
 * In Hellsing, a pair of vampiric serial killers write blasphemous messages on the walls of their victims' homes using the victims' own blood.
 * In chapter 53 of Mirai Nikki.
 * Ghost in the Shell. The General in "Solid State Society" writes "Puppeteer" in blood when that hacker forces him to commit suicide.
 * In Macross Frontier's second movie The Wings of Goodbye,.
 * In the Lupin III episode "The Wolf Saw an Angel", Goemon, to prove his Implausible Fencing Powers, cuts a series of steel beams being dropped on top of him into tiny pieces. The pieces of the beams land in exactly the right way to write out Goemon's name in kanji.
 * Played for laughs in Amagi Brilliant Park, when Tirami gets beaten up (again!) by Isuzu, and writes "Murderer has big tits" with his blood. He's not dying, and he certainly knows her name, so this is just additional sexual harassment on his part. (She clobbered him because he'd slipped a magical Truth Serum into her food and was planning to ask her lewd questions.)

Comic Books
""Did he write this in crayon?" "He used a crayon until he ate it. Then he used mustard. For the last two questions he-" "Never mind. I don't want to know.""
 * In "Calliope", The Sandman has a characteristically squicky example when Dream curses a writer with ideas. Lots of ideas. All at once. It's hard to feel sorry for him, though, considering
 * In an early Batman comic, when Linda Page is being kidnapped, she insists the kidnappers give her a moment to fix her make-up (Hey! It was the 1940s. Criminals were more polite) and writes a note for Batman in lipstick on her vanity table.
 * Played for laughs in Deadpool, when the title Anti-Hero meets up with Alex "Agent X" Hayden, wins their scuffle, then proceeds to write messages using his entrails. And steals Hayden's pancreas For the Lulz. Don't worry, Hayden can heal.
 * In a Simpsons comic, Lisa has to mark Ralph Wiggum's homework:


 * Done literally in the Squadron Supreme trade paperback; the first edition was printed with the cremated ashes of writer Mark Gruenwald mixed in the ink.
 * A writer character in Shade the Changing Man has the ability to extract the abilities and characteristics of real people for use in his stories. When he bases one character on Lenny he takes away her unique and caustic wit, and when she realizes this she freaks out by scribbling "It just isn't funny anymore" in lipstick on the bathroom mirror before.
 * In 100 Bullets, a woman writes "He's going to kill me" in her lipstick on the bathroom mirror in Wylie's gas station, referring to her husband, who she's with. (Wylie acknowledges that he received the message when he compliments the woman on her shade of lipstick.)
 * In one Mad Magazine "A Mad Look At..." feature, a dead man, having been fatally shot, used his blood to not only identify the killer (his partner), and also his motive for doing so. This is especially surprising in that "A Mad Look At..." typically has no dialogue, only Rebus Bubbles and small signs.
 * In a Superman one-shot, Lex Luthor: The Unauthorized Biography, Sands, a hack reporter who was writing Luthor's unauthorized biography was found murdered, the letter "C" written in his blood. As it was known that Sands had heated words with Clark Kent earlier, Kent was initially a suspect in Sands' murder, until a lawyer hired by Lex Luthor provided evidence that the victim couldn't have written the "C" because the angle it was written in was wrong.

Fan Works
"L: You can be incredibly creepy when you want to be. Light: Creepy? L: You question whether writing a message to someone in another's blood upon the floor is creepy? Light: I suppose you have a point there L, but it was the only writing material I knew the man would have readily available."
 * Lampshaded in the Death Note fic Low Light:

Film

 * Done by a dying man in Constantine, using a corkscrew as a pen and his own hand as paper.
 * Who Framed Roger Rabbit? had two versions of this trope using the same sheet of paper! Roger's alibi for murder is that he was writing a letter to his wife with her lipstick on a "nice, clean, sheet of paper" which
 * The Untouchables: After, Frank Nitti uses   to write the word "TOUCHABLE" on the wall.
 * In Quills, the Marquis De Sade has his writing equipment confiscated and resorts to writing on his clothes, first using red wine and eventually bodily fluids.
 * Averted in Memento where the main character is stuck without a pen and desperately needs to write something, but doesn't manage to find a workable substitute. However he does tattoo himself as a way to remind himself of important information.
 * Dr. Lizardo in The Adventures of Buckaroo Banzai Across the Eighth Dimension made a Room Full of Crazy by writing on the walls with ...chalk? Charcoal?
 * Miss Froy in The Lady Vanishes writes her name with condensation on the train window. When the heroine sees it again, it confirms to her that she's not crazy and something is amiss.
 * In Transformers: Revenge of the Fallen, Sam starts having a mental breakdown in the middle of a frat party, and in order to get the symbols out of his mind, he starts drawing them on the table... with cake frosting.
 * Journey to the Center of the Earth (1959). Explorer Arne Saknussemm leaves a message in blood on a plumb bob which—encased in a lump of volcanic rock—is retrieved centuries later by the protagonists, sending them on their journey into the Hollow Earth.
 * In Charade, a knot of conspirators are dying off one by one -  - he used his finger to spell his killer's name in the carpet.
 * In Sisters, the dying man crawls to an open window, and writes "HELP" with his bloody finger, one of the few practical examples of writing something in blood in all of filmdom, as someone does actually see him do it—and there was a possibility at that point that he might not have died if he'd gotten the attention of someone a little more quick-thinking. By the time she figures out which apartment he's in, someone has managed to finish him off, hide the body, and clean up.
 * Megamind has the titular character writing notes about his plan with a jelly donut.
 * In Terrifier, Art the Clown writes his name in excrement on the wall of the diner bathroom.

Literature
"Sophie: Why would a dying man bother to write out "P.S.", Mr. Langdon?"
 * The Da Vinci Code does this in the first chapter. Possibly includes a Shout-Out to Monty Python and the Holy Grail:

""And an answer came directed in a writing unexpected (And I think the same was written with a thumb-nail dipped in tar)""
 * In Chitty Chitty Bang Bang the children are prisoners of the mob, and are forced to write a message for help by pricking pinholes into a large-denomination franc bill.
 * In one of the Lovejoy novels, Lovejoy writes a note using his own urine as invisible ink.
 * In the Robert A. Heinlein short story Goldfish Bowl the protagonist is captured by aliens. He repeatedly scratches himself to make scars and form a message on his skin.
 * This happens repeatedly in Discworld:
 * In Moving Pictures, CMOT Dibbler tries to write down an idea for a film that came to him in a dream on his bedsheets; he runs out of bedsheet and starts writing on a wall, which he then pays a troll to carry around for him.
 * The same thing happens in Thief of Time, when Jeremy gets the idea for the Glass Clock in a dream and ends up writing the specifications for it all over his bedsheets and part of the wall.
 * In Men At Arms, Detritus, a troll, is trapped in a freezer, and the cold temperature brings his brain to peak efficiency. Unfortunately, this also means he's probably going to freeze to death, so as he gets smarter (and closer to death), he starts writing a mathematical grand unified theory of everything in the frost on the walls. He gets up to the = sign when he freezes up completely; when he's resucued, the heat from opening the door causes the rest of the equation to melt away.
 * In Thud, a dying dwarf miner uses the last of his strength to scrawl a cursed mine symbol onto the door he was trapped behind.
 * Writing an important letter in blood (complete with dramatic biting of the finger) is a great way to get across that your message is Top Priority. (That might be why in China, the Emperor gets to use red ink.) One such message is written in Romance of the Three Kingdoms in an attempt to get rid of Cao Cao; the note is found, and all of the signatories end up being fugitives of the government.
 * A mention of this trope is made in The Belgariad: When the party finds themselves in such a situation, Polgara has a quill, ink, parchment, etc, and explains that on a past occasion, she found herself needing to leave a note without the necessary implements, and ended up using her own blood to write the message. Following the event, she took steps to make sure it wouldn't happen again.
 * Subverted in the Malloreon where Belgarath curses whoever was stupid enough to write an important prophecy on human skin: The ink didn't "hold" and Belgarath was forced to go yet elsewhere to try and find that prophecy.
 * Subverted in the Agatha Christie novel Death on the Nile: a murdered woman uses her own blood to trace a letter on the wall, presumably the first of her assassin's name. It later turns out that
 * Mark Twain's The Adventures of Tom Sawyer (making this at least Older Than Radio). Tom and Huck Finn swear an oath to not talk about seeing Injun Joe murder Dr. Robinson. They write the oath on a shingle and sign it in their own blood.
 * Played with in Harry Potter. Harry is forced to do lines as punishment for telling the truth about Voldemort and is given a pen with no ink. He starts writing, and the message comes out carved across the back of his hand. Played straight in Chamber. writes threatening messages in blood while brainwashed.
 * In Mr. Bean's Scrapbook, the in-universe tie-in for the film Bean, a running gag is that Mr Bean keeps having to switch to new ways of writing: first his typewriter breaks, then his "borrowed" word processor is taken back, then he resorts to using a child's printing kit which takes three hours to lay a (mostly backward) sentence, then a pen which runs out, a crayon and a pencil which break, and finally he ends up using his own blood to refill the pen.
 * In Something Wicked, a murder mystery based on Macbeth, Duncan is found dead with "Malcolm" written on the wall of his tent in blood, which seems to implicate his son... except the hero realizes that everyone, including Duncan, called his son Mal, and it's unlikely that a dying man would have bothered with the extra letters. It turns out to be a frame-up by the real killer.
 * The Neil Gaiman-authored Sherlock Holmes/Cthulhu Mythos pastiche A Study in Emerald has the two main detectives called to the murder of the nephew of Queen Victoria (actually one of the Great Old Ones). They find the word "Rache" written on the wall in blood. Green blood.
 * In A Study in Scarlet, Holmes finds 'Rache' written on the wall in blood. Lestrade wrongly concludes that a woman called Rachel is involved, and the victim died before finishing the name. Rache is German for revenge, and the murderer
 * In the Ellery Queen novel The Scarlet Letters, a dying man uses his own blood to write XY on a wall in an extremely cryptic Dying Clue.
 * And then in the unrelated Vampire: The Masquerade story "Scarlet Letters," a girl cuts her own throat and uses the runoff to start writing poetry on the wall while she's bleeding to death.
 * The Banjo Paterson poem "Clancy of the Overflow" contains this line (known to all Australian school children):


 * Stephen King's IT has Stanley Uris, one of the protagonists, commit suicide in his bathtub because . When his wife finds him, she finds that he's written the single word "IT" on the bathroom wall in his own blood.
 * In Larry Niven's The Patchwork Girl the victim leaves "NAKF" written in his own blood on the rocks of the lunar surface.
 * In Jonathan Strange & Mr Norrell Childermass briefly attempts to copy, onto his own flesh. He quickly gives up for some of the many, many reasons no one should ever even try to copy out something in a language they don't know onto their skin, with a penknife, all alone in a cold and isolated area,
 * In New Moan (a parody of the Twilight saga), this trope is played with. Teddy (the Edward Expy) gives Heffa (the Bella Expy) a note, written in some red substance. Heffa asks if it's blood, to which Teddy replies that blood is useless as ink since it clots too quickly, and it's just normal red ink.
 * Thicker Than Water has Felix called out to a crime scene where his name is written in the blood. Lampshaded in narration: "The words 'Use a pen, Sideshow Bob' flitted incongruously through my brain."
 * In A Song of Ice and Fire people who join the Second Sons traditionally sign in blood. They abandoned this tradition some time ago and started using red ink instead, because blood makes terrible ink.
 * This trope is precisely the reason Polgara always carries ink with her.
 * In Brazilian book A Droga da Obediência, one of the protagonists is captured inside the school. Just before being dragged out of the place, he asks his kidnapper to go to the bathroom, and uses the contents of a toilet to write a Morse code message to his friends.
 * The Eighth Doctor Adventures gives us the two-novel story Interference, wherein winds up using his own blood to cover the floor of his cell with arcane mathematical formulas.
 * In The Rebel of Rhada by Robert Cham Gilman (Alfred Coppel), one of the aristocratic plotters realizes he's effectively betrayed all humanity to a killer cyborg, which is more evil than he'd planned on. He commits suicide ... after cutting a warning into his chest. By lucky chance, his corpse comes to the hero's attention and gives enough of a hint to let him know what kind of menace he's facing.

Live-Action TV
"The two see Get Out! written in red on the wall. Mitchell: Oh, Shit! George: Shit! What is it, blood? Mitchell: Paint, And it's still wet. Tch. Blood. You ever try writing anything in blood? It's totally impractical."
 * Happens from time to time on NCIS, generally of the giving-a-clue-as-to-the-murderer variety. Except for the time it was a call for help. Unintentionally aimed directly at a NCIS investigator. ...Which also ID'd the person making that particular call for help.
 * From a deleted scene of Being Human:

""Get the woman a pad! A PAD!""
 * Becker: "Look, writing your name in the snow with your pee is good drunken fun when your name is something like Joe Smith. But, when your name is Stanislav Kasacinski and it's ten below out, you're just frostbite waiting to happen."
 * Red Dwarf has a dying Red Shirt scrawl a warning using blood and intestines. The Cat wonders why he went to the trouble of using his kidney as a full stop. Rimmer notes that it probably just "plopped out" on its own. In Better Than Life (the book), the crew get stuck in a virtual reality game and the only way to communicate with them is by carving messages into their arms.
 * There's an episode of Friends where Phoebe writes a phone message on the back of Chandler's neck.

"Bert: He's improving. Last time he used spaghetti sauce."
 * Top Gear Jeremy Clarkson declared that the Dodge Viper was a car "so sophisticated, it could write its own name." He then proceeded to write the word 'Viper' on the test track, using skidmarks.
 * Angel used this trope a lot for ghosts. In season one, a malevolent spirit wrote messages on the walls of Cordelia's apartment. In season five it was the messages in the condensation of Fred's shower door.
 * Legal documents at Wolfram & Hart are shown being signed in blood.
 * Jonathan Creek used the contract-signed-in-blood version in the season three episode The Curious Tale of Mr Spearfish.
 * A classic Sesame Street sketch has Ernie writing a shopping list with chocolate pudding, because he couldn't find a pen, a pencil, a crayon or a typewriter.


 * Blackadder: "I'm sending off some party invitations and to make them look particularly tough, I wish to write them in blood. Your blood, to be precise."
 * Seen in the Torchwood episode, "Captain Jack Harkness." Tosh and Jack are stuck in the past, and need to send a message that will last the next 60 years and be found by the other members of their squad. Tosh doesn't have a pen, so she cuts her hand open on a rusty can and writes in her own blood. Also seen in "They Keep Killing Suzie." The word "Torchwood" is written in blood on a white wall on a crime scene.
 * Doctor Who is a fan of this trope, as well. River Song, in particular, once used a blowtorch to write "Hello Sweetie" in high Gallifreyan on a starship's black box to be found by the Doctor 12,000 years later. She also carved a message on the diamond cliffs of planet One, making it the oldest written words in the history of the universe, because the Doctor wouldn't answer his phone.
 * Turn out she learned this technique from her parents, Amy and Rory, who used a car to make a crop circle reading "DOCTOR" in order to get his attention in "Let's Kill Hitler".
 * The opening episode of Season 4 of The X-Files had writing a message in blood on Mulder's doorstep, having been shot trying to bring information.
 * In Buffy the Vampire Slayer, after Angelus kills  the day he had sex with Buffy, he writes a message to Buffy on the wall -- "Was It Good For You Too?" in the victim's blood.
 * Played for laughs in this comedy sketch by Jinnai Tomonori.
 * John Crichton in Farscape lured Scorpius into a trap by using the complex-looking equations for wormhole navigation written in blood on the floor of the holding cell. It was rather obviously ketchup.
 * In the Charmed episode "The Power of Three Blondes," the Halliwell Sisters are replaced by three evil blonde impostors who are all Brainless Beauties. While impersonating Phoebe, Mitzy Stillman gives Phoebe's newspaper-editor a report written in eyeliner (she was intentionally trying to get Phoebe in trouble with her boss). When explaining why it's written in eyeliner, Mitzy claims that, you guessed it, "I couldn't find a pen."
 * The Sarah Connor Chronicles had one of these which was even more absurd than the usual examples of this trope. In the beginning of the second season, a guy makes the jump from the future to the past but is shot when he does so. He needs to get his message to Connors, so what does he do? He breaks into their basement and scrawls a confusing and incoherent message on the wall with his own blood then visits upstairs, whispers something cryptic then dies. He sure failed at that mission.
 * In the pilot episode (Days Gone By) of The Walking Dead, Rick comes across an abandoned farmhouse where the two former inhabitants had scrawled "God Forgive Us" in blood on the wall before committing suicide.
 * A sketch on Blue Collar TV had Larry the Cable Guy calling Information for the number to 911 and, not having a pen, bit the tip off a strawberry to write it on the wall.
 * Starsky and Hutch has two opposed examples. In the episode "Bloodbath", Starsky is kidnapped by a murderous cult, who leave his name scrawled in blood on a mirror for his partner to find. In "The Plague", Hutch is in an isolation room with a fatal disease; before Starsky leaves to go look for a cure, he uses a borrowed lipstick to write his name on the observation window where Hutch can be reassured by it.
 * Luther. A satanist killer abducts a woman from her home and leaves the corridor leading from the front door covered in words written in blood such as DO NOT FEAR THE ABYSS, I AM THE ABYSS. Likely a deliberate use of the trope to add to his reputation and creep people out. Also a deliberate taunt to the police, as the blood had been kept frozen from a murder the police had been unable to pin on him years before.
 * On FlashForward, when, he tries to write a note like this, using his blood as ink and a flyer for paper.
 * In 2point4 children Ben witnesses a hit-and-run and rushes into the kitchen shouting the car's registration number (license plate) over and over so he won't forget it. Not having a pen, Bill writes the number on a cucumber with a tube of mustard.
 * CSI: NY did a variant where the victim didn't write the message-it was written by the killer in an attempt to implicate someone else.
 * An episode of the Live-action Largo Winch shows a woman joining a group of villains, and signing her name with her own blood.
 * The angel-banishing sigil on Supernatural does not count, as it has to be drawn in blood or it doesn't work. However, there was an episode where Sam drew a devil's trap (which does Exactly What It Says on the Tin) in his own blood for lack of any other medium.

Music
"Man: ...it was a message, scrawled in his own blood. Man 2: What did it say? Man: "See you next Wednesday.""
 * In the John Landis-directed video of Michael Jackson's "Thriller", we hear:


 * Parenthetical Girls are hand-numbering their latest album in their own blood.

Tabletop Games

 * Dungeons & Dragons module I12 "Egg of the Phoenix". A revenant [undead creature] will try to communicate by writing a message using its own decaying flesh.
 * In the Planescape setting, a cleric of a god of communication once tried to use magic to communicate with The Lady. After The Lady's shadow had passed over her, the cleric arose as a vampire that was unable to communicate in any way except by using people's intestines to form words. To compound the problem, a rumour arose that The Lady had indeed said something to the cleric, leading to someone actually seeking her out to find out what. She was apparently happy to comply, but ran out of guts before she could finish.
 * Warhammer 40,000: The scribes of the Grey Knights chapter use blood to write the true names of daemons, as apparently using ink gives the demon some power over the writing.
 * Abyssals in Exalted have a Charm that allows them to write in their own blood without suffering any harm from the blood loss.

Video Games

 * Twice in the Ace Attorney series there has been victims who wrote names, presumably of their killers, in blood. Apollo Justice has a victim writing a number on the floor in his blood, which is then cleaned by his assassin.
 * There's also the case concerning Maggie, whose boyfriend wrote her name in the sand next to him with his right hand before he died.
 * In the demo case for Gyakuten Kenji, another prosecutor finds that the victim (supposedly) wrote Gumshoe's name in his own blood on the crime scene. As Edgeworth, you have to demonstrate that the detective must be innocent.
 * In Chrono Trigger, you find a fallen knight who gives you a monster-fighting tip using his blood as the ink. Good thing he was a knight instead of a writer of strategy guides...
 * Dead Space has "Cut off their limbs!" written in blood around the ship. It's good advice.
 * Portal has loads of insane messages scrawled in... Uh, it's hard to tell what it is actually.
 * Frosting?
 * We all know why that can't be.
 * According to the webcomic tie-in for the sequel, it's just paint.
 * BioShock (series) has a number of messages written in blood, most notably the message on the board of photos reading:
 * In System Shock 2, there are walls with bloody messages urging players to.
 * When you reach Delta Labs 4, the epicenter of the demon invasion in Doom 3, the walls are streaked with bloody messages. Whether it was done by demons, demon-possessed victims or just by insane victims, there are no survivors left by the time you arrive. The words repeated over and over again are "suffer", "die" and (appropriately enough for being on the edge of a Hell Gate) "burn".
 * In Wing Commander Prophecy, it's not shown, but in a discussion between some NPCs in the pilot's lounge, it's said that the Kilrathi aboard the kat fleet that got wasted earlier in the game used their blood to write "Knathrak", roughly equivalent of Ragnarok for them.
 * At the end of Assassin's Creed, Desmond gets to see some elaborate drawings made by subject 16 in blood. There are so many of them that one has to wonder how he managed to keep the drawings so neat.

Web Comics

 * Parodied. When the cast of Ansem Retort played Pictionary, Axel drew his in Riku's blood for kicks.
 * In Juathuur, Rowasu uses blood at the end of chapter 11.
 * A particularly awesome moment in Kagerou has Dark, bleeding from his, writing the names of Red's victims in blood, as well as revealing Red's true name,.
 * In Schlock Mercenary, Kevyn Andreyasn uses his blood to write a warning for Captain Tagon, as the same injuries that gave him blood to write with prevent him from speaking. As the next page shows, it's really, really urgent.
 * In Homestuck, Vriska mind-controls Tavros into writing text with her blood... for him to read.
 * And then he wears his fingers down, and the writing becomes in his own blood.
 * has a really fricking creepy variant.
 * Superego has Juliet do this with milk-based paint, and she does it often, driven by her desire to tell others about her psychic dreams and their potential meanings.
 * A nanotechnology reservoir in Last Res0rt is hidden behind a door with some warning scrawled in blood in an alien language.
 * The introduction of the girls in CRFH has Roger slipping a note under their door. Unfortunately, he forgot to bring a pen, so he wrote the note using blood produced by a convenient papercut. Also, the cut stops bleeding before he can finish writing the message, so what the girls find reads more like a death threat from a stalker than an invitation to dinner (Which is what the note was intended to be).

Web Original
"Light: First I gotta get my stupid watch open. Aw, there we go... L: What's that Light? Light: Oh I'm just excited we caught Kira is all. Hey look, they're bringing him in right now... Ow! L: Are you okay? Light: Yeah I'm fin-OW! I'm okay OW! DAMMIT! L: Light, do you need me to come over there? Light: No, no. I'm okay. I'm just so happy that it hurts. Kinda like a little prick."
 * Slightly done in Draw With Me, where, oddly enough, they use coal on glass, which makes no sense.
 * However, it could have been black chalk, and we don't know exactly what the wall is made out of. (It's some durable glass, if it even is some sort of supernatural sentient self-repairing glass.)
 * The Nostalgia Critic, after the IT review, and, using, writes the word "Balloons" on the wall..
 * In the MSPA fan adventure The White Depths, a cleric blesses a weapon by writing runes on it, but has nothing handy buy his own blood. It's just as well though, since one's blood is the best vector for a cleric to channel his magic.
 * In Death Note the Abridged Series Kpts 4 tv when Light is  by writing  's name with his own blood and ends up stabbing himself repeatedly. Hilarity Ensues:

Western Animation
"Bart: Maybe it was one of the other Barts that- Skinner: There are no other Barts!"
 * The Simpsons
 * In "Principal Charming", Bart wrote his name in the schoolyard using grass-killing chemicals.


 * In "Cape Feare", Sideshow Bob writes death threats to Bart in blood. And his diary. And amusing letters to Readers Digest. When he starts feeling faint, Snake suggests that Bob get a pen.
 * Subverted when the family goes over the threat letters and finds one in pen; Homer admits he wrote that one after Bart somehow tattooed "Wide Load" across Homer's ass.
 * In "The Springfield Files" Homer runs away from an alien screaming "Yahhh!" As we watch from above we see him run through a field spelling out the word "Yahhh!" in cursive (including the exclamation mark, which he dots!)

Real Life

 * Of the second variety (because it's cool and symbolic), it is general knowledge in Philippine history that members of the anti-Spanish revolutionary group Katipunan (literally "commune" or "brotherhood") sign their membership forms with their own blood drawn from their forearms as a sign of commitment to the struggle. It was never known whether members suffered from tetanus or infection, but who cares?!
 * The Marquis De Sade, after being imprisoned, wrote his stories on his own body, first using wine and a chicken bone, then his own blood.
 * The Manson Family had a creepy habit of writing things on walls at murder scenes - in the blood of the victim.
 * The murder of Frenchwoman Ghislaine Marchal in 1991 involved her writing in her own blood on a wall: "Omar m'a tuer" ("Omar killed me", with a glaring spelling mistake.) The phrase is still very famous in France (perhaps due to the controversial nature of the whole thing: The case is still sort of unsolved).
 * Apparently, several people have made last-minute testaments in this way: There is a story about a farmer, trapped under his own tractor writing on the bumper, with mud, who of his neighbours would get which of his animals and about a dying man who wrote "all to wife" on the wall in his own blood. Both of these were accepted as valid.
 * Saddam Hussein had a copy of the Qur'an written in his own blood... even though blood is seen as unclean in Islam and writing a Qur'an with it is a very high blasphemy. Of course, destroying any copy of the Qur'an is also blasphemy.
 * IIRC, the guy who wrote the lyrics to the Moroccan national anthem wrote it in his blood on his cell wall. It must have looked like a Room Full of Crazy.
 * Geocachers who hike several miles to a cache to realize they left their pen in the car have been known to sign the logbook in blood. The preferred way is to make a mark with dirt or mud and explain it in your note online.
 * Apparently, this was once inverted: The murder victim had a pen and wrote the killer's name on her body. Unfortunately, the conditions the body endured made it unreadable until the FBI's Special Photo unit used an infrared camera to get a better image. The guy was caught.
 * When Fracisco Pizarro - the Spanish conquistador who led the conquest of Peru - was assassinated, he was stabbed through the throat. Reportedly he drew a cross in his own blood and kissed it before dying.
 * When the last Mughal Emperor (who was a noted poet) was exiled from Delhi by the British for supporting a major rebellion, he wrote poems on the walls of his room with a burnt stick.
 * Reportedly, North Korean military units sometimes used their blood for the signatures on unit-wide pledges of loyalty to the current ruler. Kim Jong-il asked them to stop, because draining themselves for this "ink" would make them less fit and strong to "resist American aggression."

THEYRE COMING