Kryten: The poor devil must've scrawled it in his death throes, using a combination of his own blood and even his own intestines.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. There may be Bloody Handprints nearby as well. May cross with Blood-Stained Letter as well. 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. Sister trope to Condensation Clue.
Rimmer: Who would do that?
Lister: Someone who badly needed a pen.
Rimmer: Who would do that?
Lister: Someone who badly needed a pen.
— Red Dwarf, "Psirens"
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Anime & Manga
- 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..."
- In Death Note Light keeps a piece of death note paper and a pin for pricking his finger and writing in blood (couldn't fit a pen?) concealed in a secret compartment of his watch, so that he can kill someone quickly and discreetly if necessary. He first uses it to kill the third Kira when he becomes a liability rather than an asset, while L is sitting right next to him. In the final episode after getting his pen destroyed by Matsuda while trying to write down Near's name in the pages of the titular Artifact of Doom, Light continues writing with his own blood, which prompts Matsuda to blast the living snot out of him. 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.
- Happens all the time to victims in Detective Conan.
- 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.
- Ghost in the Shell: Stand Alone Complex. "Puppeteer'' is written in blood by the General in "Solid State Society" after he's forced to commit suicide by the hacker.
- In Hellsing, a pair of vampiric serial killers write blasphemous messages on the walls of their victims' homes using the victims' own blood.
- During their first encounter with Alexander Anderson when Alucard gets pureed, his sentient blood writes a message to Seras all by itself.
- In Part 3 of JoJo's Bizarre Adventure, when Kakyoin encounters Death in his dream world. he realizes that anything that happens to him also happens to his body in the waking world. So to help him remember that the infant child is actually Death's user, he takes a pocketknife and carves the words "BABY STAND" into his forearm. However, revealing this to the rest of the crew doesn't do him much good in convincing them that he isn't insane.
- In the Lupin III (Red Jacket) 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.
- In Macross Frontier's second movie The Wings of Goodbye, Sheryl Nome writes the lyrics to the eponymous song on her wall in her own blood.
- 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 chapter 53 of Future Diary after the second Yuno is stabbed by the real Yuno, the other Yuno uses her last moments of life to write "Help Me" on the wall in her blood.
- In Naruto: Jiraiya etches a dying message on a toad's back.
- In Princess Tutu, Drosselmeyer is said to have written a story in his own blood after the Book Men cut off his hands. Yes, it's implied he used the stumps.
- Rurouni Kenshin: Rather than die in prison, Shishio's Dragon Houji commits suicide by slitting his own throat, and, in his final moments, writes a chilling message on the cell wall with his blood:
This world is dead to me. I will follow my master to Hell.
- 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.
- While in Soul Eater Not! The final part of Episode 6 has the message say this "While you are sleeping. We still awake and keep watching". this is NOT for parody.
- In Mobile Suit Zeta Gundam Enigmatic Minion Paptimus Scirocco signs a written pledge of his loyalty to Big Bad Jamitov Hyman with his own blood. Naturally, this means he eventually betrays Jamitov and usurps his position as leader of the Titans.
- In A Certain Magical Index, Umidori Kuroyoru gets assaulted by Rensa and is left barely able to talk. She manages to warn Shiage about Rensa by writing in her own blood.
- Attack on Titan: When Reiner writes into the Female Titan's hand with his blades in Episode 17
- In "Calliope", The Sandman has a characteristically squicky example when Dream curses a writer with ideas. Lots of ideas. All at once. Making him try to scratch them out on the walls with his fingertips. It's hard to feel sorry for him, though, considering he kidnapped and imprisoned the titular muse of poetry just to get ideas for stories and get rich. He also rapes her from time to time, too.
- 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.
- 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 trying to kill herself.
- 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 "A Mad Look At..." 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 RebusBubbles and small signs.
- Carnage does this all the time, writing "CARNAGE RULES" in blood in big letters near his victims, often using his own blood when he can't use someone else's. (Spider-Man knows he's dealing with "one sick puppy" the first time he realizes that.)
- 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. At the end of the story, it was revealed(but not to the police) that Luthor had Sands killed and Kent framed, and then sent his lawyer to prove Kent's innocence. The lawyer then told Kent that Kent now owed Lex Luthor a favor.
- Batman Vampire:
- In Red Rain, after being slashed across the chest by Dracula, Batman uses it to his advantage to draw the image of a cross on the wall in his own blood. Dracula is left at a stalemate, both drawn to the blood and unable to approach the cross, and is ultimately forced to flee when the sun rises.
- In Crimson Mist, after slaughtering every homicidal inmate in Arkham Asylum, Batman leaves a note to Dr. Arkham in blood. The note reads, "Go home. Your work is done."
- Lampshaded in the Death Note fic Low Light:
L: You can be incredibly creepy when you want to be.
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.
- Appears in Kingdom Hearts story I'll Never Be Enough when Cenchaze writes his goodbye (and several other notes) in his own blood.
- Happens in the Pony POV Series Dark World Series. While sending the murder of blackbirds that have been tormenting Derpy for the last thousand years to Ponythulhu's realm, Twilight takes time to write a letter with a blackbird pie recipe to the big guy because Ponythulhu is actually a pretty nice guy and they want to be respective to him. Since she ''literally' doesn't have a pen, she pulls one of Spike's (now a giant adult dragon's) scales off and writes the letter in her blood. Justified in this case because finding a pen in time wouldn't be possible, and Twilight has Complete Immortality and will just regenerate the lost blood.
- The Room 101 in Hivefled is covered on all four walls and the floor with messages carved with the prisoners' fingernails.
- In Moratorium Harry draws anti-Apparation runes in her blood.
- In Death Note: The Abridged Series (kpts4tv) when Light is killing Higuchi by writing Higuchi's name with his own blood and ends up stabbing himself repeatedly. Hilarity Ensues:
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.
- In Guardians, Wizards, and Kung-Fu Fighters, as all of reality collapses due to Shendu destroying the Book of Ages, Jade grabs ahold of a remaining scrap and — lacking anything else to write with — chomps on her finger and uses the blood to scribble out an assurance of safety for her family and friends, thus triggering the resulting merger of universes.
Films — Animation
- Megamind has the titular character writing notes about his plan with a jelly donut.
- In The Incredibles, Gazerbeam used his laser vision to zap the word "KRONOS" into the wall of the cave he died in. Mr. Incredible finds it and eventually figures out that it's the password to the latest project that Syndrome's been planning.
- In Batman Beyond: Return of the Joker, a scene involves Bruce Wayne being found after an attack by the joker with "Ha! Ha! Ha!" written on the ground in red. It was changed to purple in the censored version to avoid looking like this trope.
Films — Live-Action
- Done by a dying man in Constantine, using a corkscrew as a pen and his own hand as paper.
- Who Framed Roger Rabbit has 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 turns out to be Marvin Acme's will (the MacGuffin of the movie), which has been written in ACME's Disappearing-Reappearing Ink.
- The Untouchables: After murdering Oscar Wallace and George the Bookkeeper in an elevator, Frank Nitti uses their blood 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 8th 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 Saknussem 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 Harry Potter and the Chamber of Secrets the Heir of Slytherin wrote their threatening messages on the walls in blood. In the book they were just paint. Ginny probably wouldn't have that much blood in her anyways.
- In Charade, a knot of conspirators are dying off one by one - James Coburn's character is found with hands and feet bound to furniture legs and a plastic bag over his head - 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.
- Played for Laughs in the Hong Kong comedy Justice My Foot. Stephen Chow plays the protagonist Sung Sai Kit, a cunning lawyer who wins via clever ploys and his wits (seriously, he wouldn't be out of place in the Ace Attorney universe). Jailed towards the end of the movie, he has to get the attention of the high magistrate, and as he is in prison, has no access to brush and ink. He writes a message in blood on a fan... by biting the finger of the man who presents the fan to him as evidence of innocence in a previous incident, and using said finger as a brush instead of biting himself, as is expected by Asian sensibilities.
- Welcome to the Punch (2013). A female detective has a habit of writing notes on her hand, instead of taking out a notebook. When the protagonist finds her dead at the morgue, the final vital clue is there for him to act on.
- As Detective McCarthy searches for Jenke in the opening flashback of The Horror Show, he comes across of one cop's severed head placed on a table with "blue platter special" written in blood on a wall next to it.
- Outpost. After the first two mercenaries die, Prior heads out of the bunker with a bed sheet marked "5" to tell the undead Nazis just how many are left, then tells them to "bring it on". When they kill Mac, the Nazis then respond in kind by tying his corpse to the post, with a "4" carved into his chest.
- A variation in Abel Gance's Napoléon. Marceau does have a pen and paper but there is no ink, so he pricks his wrist and signs the army register with his blood.
- Another variation in The Killing Room (2009). Several people are locked in a white-painted room and forced to take part in a lethal Mind Control experiment. One of them finds what appears to be a message from the previous occupants scratched into the wall. The words have been painted over, so they take the blood from a member of their group who has already been killed and smear it on the walls to make out the words. A cut later there's blood smears all around the room, showing they're just the latest of many victims. Turns out the words have been put there deliberately by the researchers, so having to use blood to see them is likely a deliberate Mind Screw.
- The Night Flier: The vampire writes a message in blood on Richard Dees's motel room window: "STAY AWAY". Dees doesn't listen.
- Downey in Triangle, after getting his throat slashed, lives long enough to attempt to scrawl the name of his killer on the mirror in his own blood, but dies partway through.
- Mystery Date: The man in the upstairs room of Club Voltaire scrawls two clues in his own blood on the wall.
- In the 1932 film Three on a Match, Vivian scrawls a message in lipstick on her nightgown and throws herself out the window of the fourth-floor apartment where she and her son are being held, alerting the authorities and saving her son's life at the cost of her own.
- The Duellists. The protagonist's girlfriend writes 'Goodbye' on his sabre in lipstick when she leaves him. The lipstick is blood-red, which is appropriate given he was about to fight a Duel to the Death.
- At one point in Mad Max: Fury Road, Max can be seen using his blood to draw a map.
- A variation in The Last Witch Hunter, as 36th Dolan leaves his final message to Kaulder by marking proper words in his journal with his own blood.
- Soldier of Orange: When Erik is arrested by the Germans and put in prison, he writes a letter to the warden asking for his release using toilet paper and his own excrement. The Germans are not amused.
Warden: Man, have you gone mad?!
Erik: I didn't have a pen.
- Resurrection: Subverted. The cops find a message left behind by the killer at his first murder site written on the window in blood: HE IS COMING. However, lab tests show it to be lamb's blood.
- Dead in Tombstone: As Guerrero kills each of the gang and places their bodies in coffins outside the church, he pins a page of the bible to their chest with a knife and writes their number on it in blood.
- In While the City Sleeps the killer writes "Ask Mother" on the victim's wall in lipstick.
- The Dark Tower (2017). Walter burns Jake's mother in their own home, and draws a smiley face and taunting message on the wall using her ashes.
- In Kung Fu Hustle, Sing has been beaten to a pulp. The Landlord and Landlady, thinking he's dying, ask if he has a last request. He draws a lollipop with his blood before passing out. The two complain he should have written out the request because they have no idea what he drew.
- 10 Cloverfield Lane. Michelle has become reconciled to her confinement in the bunker until she discovers the word HELP scratched on the inside of the viewing window of a locked hatch to the outside world. She finds an earring used to make the scratches lying on the floor below, which also appears in a photograph that Howard said was of his daughter, but is actually a girl who went missing a couple of years before.
- The Da Vinci Code does this in the first chapter. Though he only used the blood to make the police use ultraviolet lamps. He did have and use a pen, but one with invisible ink (except in UV). Possibly includes a Shout-Out to Monty Python and the Holy Grail:
Sophie: Why would a dying man bother to write out "P.S.", Mr. Langdon?
- 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 rescued, 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.
- Older Than Print: 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.
- Discussed and averted in The Belgariad: When the party finds themselves in such a situation, Polgara has a quill, ink, parchment, etc. ready to hand. She 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 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. This doesn't work because Poirot, Race, and Dr. Bessner are all smart enough to know the victim would have died instantly and couldn't have written anything after being shot. The only reaction it produces is a snarky comment from Poirot that killer is apparently a fan of old-fashioned melodramas. It later turns out that the killer wrote the letter. In a double-twist on this trope, it was written to implicate one of the people actually directly involved in the murder, in an attempt to make it look like another party was trying to frame her.
- Mark Twain's The Adventures of Tom Sawyer. 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 and the Order of the Phoenix. 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.
- 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 ( not Watson and Holmes) 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, Sherlock 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 who was American intended for the police to believe it was committed by a German. Holmes wasn't fooled when he noticed that too much effort went into making the handwriting look German. The blood is also not from the victim, but from the murderer whose nose bled because of the excitement.
- 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 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):
"And an answer came directed in a writing unexpected
(And I think the same was written with a thumb-nail dipped in tar)"
- Stephen King's IT has Stanley Uris, one of the protagonists, commit suicide in his bathtub because he doesn't want to go back to Derry to face It again. 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. He was trying to write "NAKED" indicating that his killer was naked: i.e. not wearing a space suit, which is quite a trick out on the surface of the moon.
- In Jonathan Strange & Mr Norrell Childermass briefly attempts to copy the Book of the Raven King, which had been written as blue discoloration on a man's skin, 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, when the book covered the man's entire body except for groin, face and hands, and for all he knows size and placement of the marks is vital.
- 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. When he joins the company, Tyrion mixes some of his blood into the ink he signs with.
- Stannis Baratheon uses his own blood to sign an accord with the Iron Bank of Braavos, because his ink has frozen.
- 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 the Doctor winds up using his own blood to cover the floor of his cell with arcane mathematical formulae.
- In A Brother's Price Jerin was burning a letter when people came through secret passages and abducted him. He struggled for long enough to be able to write one three-letter word in soot before they hauled him away, the name of the one he thought responsible. Many characters in that world are illiterate, and they didn't have time to clean up as his bodyguards were trying to break through his locked door.
- In The Laundry Files the Official Secrets Act and other non-disclosure agreements have to be signed in blood — a sterile lancet or disposable needle and Sharps container are thoughtfully provided.
- In Hours, the ninth class to inherit the secret gymnasium discovered that the 8th class had stolen all the markers out of the gym. Since the scanner at the door prevents anybody from bringing foreign objects into the gym, the ninth class had to write the rules to their game using blood. The tenth class avoids this by writing their rules using the poison ink secreted from a plant Alexis grows.
- In the Mageworlds novel Starpilot's Grave, a Magelord is revealed to have cut the throats of those piloting the warship he was riding and used their blood to write a cryptic note to an "Adept from the Forest World" on the windscreen before emptying the craft to vacuum, swiping a scout-craft, and setting it adrift on a sub-light trajectory which would bring it to the attention of the recipient some five centuries after the fact... and a few months after the death of said Magelord.
- In The Deluge, Kmicic writes a letter with his own blood to make sure the other party knows he is not lying.
- In Heaven's Queen, third book of the Paradox Trilogy, Maat writes out a message for Devi using Devi's own blood while Devi is unconscious.
- In Mr Meeson's Will by H. Rider Haggard, a dying millionaire trapped on a desert island has his will tattooed on the back of a fellow castaway.
- The demon summoned by David Krake in the second part of Princess of Wands uses the blood of some of his victims to continue the runes that his summoner wasn't able to finish after taking three arrows to the head.
- In Geist, the protagonist's sidekick discovers a rune written with blood while looking for a missing person. Apparently the blood wouldn't have been strictly needed, so it was a case of the missing person not being able to get a pen.
- In The Girl From The Well, Yukiko Uchiyama's ghost has scrawled phrases in blood on the walls of her house.
- One of the villains in The Court Of The Air is fatally impaled during a sword fight in an open snowy field, by a fugitive he knows has been living under a false name. As he's dying, he tries to pass word of his foe's hidden identity using his own blood to write it down. In this case, the Dying Clue aspect of this trope is subverted, because the snow he writes the man's secret down on melts before his body can be found.
- Happens in the first book of the Lionboy trilogy: Charlie's mother grazes her leg when she falls off a ladder, but before bandaging the wound she asks Charlie to bring her a pen. Charlie brings her an old fashioned nib pen and ink, but she ignores the ink in favor of dipping the pen in her blood to write a mysterious note.
- 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.
- 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.
- In an episode of Babylon 5 this trope is subverted and played straight; one of the monks, Brother Edward, sees "Death Walks Among You" written in blood on the wall, but that one turns out to be just a compund that looks like blood, then vanishes after a couple hours so people think he was hallucinating. The monk is a former Serial Killer who was subjected to a mind wipe, and a telepath was hired by families of his victims to break the programming before they took revenge. The straight use of the trope should be fairly obvious: at the scenes of his crimes, he actually did write "Death Walks Among You" in the victim's blood on the wall.
- From 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."
- From a deleted scene of Being Human (UK):
[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.
- 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."
- Blake's 7: One episode was an "old-fashioned" whodunnit on a spaceship. One member of the crew was found dead with the cryptic message 54124 written in blood beside him. Avon reasons that "When you are dying, it is difficult to be neat", and announces that the guilty party is a suspect whose name is SARA.
- 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.
- In an episode of Bones, Bones was being framed for the murder of a friend incarcerated in a mental hospital. It eventually turned out that the victim had left a long and complex clue by writing in his own saliva which only showed up under a blacklight when Hodgins and Cam search his room looking for a clue in a triangle.
- Buffy the Vampire Slayer:
- After Angelus kills Jenny's uncle 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.
- In Conversations With Dead People Dawn sees what appears to be her mother, and the incredibly creepy words 'Mother's milk is red today' appear on the wall. Unlike in the first example, this blood was red not brown. Because Rustproof Blood was averted in the first instance, it can be assumed that this blood is actually meant to be fresh.
- An episode starts out with a murder victim who wrote "LIE" on the ground with her blood as she lay dying. Turns out they were looking at it upside-down: it was actually the number "317".
- Another episode had "Murdere" written in the victim's blood on a mirror. For a while Castle muses that it implies the killer is foreign "Murdere, he's French! Murdero, he's Spanish!" (The final letter wasn't very clear and could have been E or O.) It was written by one of the two (yes, two separate) killers in an attempt to frame an extreme animal rights group that had been protesting the victim's company for animal testing.
- 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."
- In "Passed Pawns, the Victim of the Week uses his dying strength to write the letters 'D E' in his own blood on the floor of the alley.
- In "CSI Unplugged", the kidnapper leaves a note saying "WE HAVE HARPER" written in blood.
- 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.
- Death in Paradise: In "A Murder on the Plantation", the Victim of the Week is hit with a machete and uses his dying strength to write the letters ' J O H' in his own blood.
- Drop the Dead Donkey. Seen during Globelink's so-called 'reenactment' of a post office robbery that (thanks to Gus Hedges desire to recreate Reservoir Dogs instead) gets played for Bloody Hilarious fanservice, including a shotgunned postal worker scrawling I LUV YOU MUM on the wall as he dies.
- 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.
- Amy and Rory use a car to make a Crop Circle reading "DOCTOR" in order to get his attention in "Let's Kill Hitler".
- A variation of this trope appears in "The Invasion" starring Patrick Troughton as the Doctor. One of the characters in the story has the habit of scribbling notes on her apartment walls using the irrefutable logic, "You can lose a piece of paper, but you can't lose a wall."
- "The Day of the Doctor". The War Doctor blasts his NO MORE message into a wall using a laser gun he borrows from a Gallifreyan soldier.
- An arc of Earth: Final Conflict had an prison inmate who drew alien symbols on his cell with his own blood. They were of huge importance for the resistance, as they knew hardly anything about the Commonality at the time.
- In Elementary, a shooting victim uses his blood to write a message that the shooter was not his estranged brother, to keep the brother from being a suspect. Other characters point out that given that he took the time to write in his blood, the message is genuine. The estranged brother is the one who points out, quietly and privately, that since the victim was shot in the back, they couldn't actually have been completely certain that it wasn't him.
- 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.
- Bonus points for not only hiding the key piece of the equation under his foot, so Scorpy had to come in to get it, but threatening to wash the whole thing away in his own blood if Scorpy didn't.
- On FlashForward, when Lloyd Simcoe is kidnapped by Flosso, he tries to write a note like this, using his blood as ink and a flyer for paper. It's blown away though, and only found after he's rescued.
- There's an episode of Friends where Phoebe writes a phone message on the back of Chandler's neck.
"Get the woman a pad! A PAD!"
- In the Haven episode "Real Estate", an evil house kills a woman, and her dripping blood spells out, "This is your fault."
- Human Giant has a Paul killing a someone and writing a message on the wall... Turns out that it's a reminder for Aziz's dentist appointment.
Aziz: (looking at a pile of corpses) Man, we really need to get a marker board or something. This is gettin out of hand.
- Played for laughs in this comedy sketch by Jinnai Tomonori.
- Jonathan Creek used the contract-signed-in-blood version in the season three episode "The Curious Tale of Mr Spearfish".
- An episode of the Live-action Largo Winch shows a woman joining a group of villains, and signing her name with her own blood.
- Law & Order: Criminal Intent: In "Three-In-One", the killer, who suffers from dissociative identity disorder, paints on the wall in his victims' blood, and one of his personalities writes messages asking for help.
- 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.
- The Mentalist has the main bad guy, Red John, write a symbol on the wall with his victim's blood, which drove the main character to work with the police to try to catch Red John.
- Mission: Impossible: In "Command Performance", a thief dying in a church writes "1769" on the floor in his own blood as a clue to the location of his stolen loot.
- Subverted in an episode of Monk: Sharona finds a message scrawled in red on a wall... but it turns out that it's just lipstick. Her lipstick.
- Murdoch Mysteries:
- In "Bad Medicine", the Victim of the Week writes the letters "W Y" in his own blood on a rock after he is shot in the back with an arrow.
- In "Snakes and Ladders", the killer writes the words "TRY TO STOP ME" in his victim's blood at the sites where he dumps their bodies.
- In "The Murdoch Appreciation Society", Murdoch uses his ultraviolet light to check for blood stains at a scene and finds the phrase "BLUE SKY" also written in blood.
- 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.
- In the season 4 finale of Once Upon a Time Henry gets hold of The Author's Pen to undo the cruel story inflicted on his family, but no ink. So he dips it in Regina's open wound.
- 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.
- Rome. Lacking a wax seal for a dispatch, Octavian grabs a handful of manure from the battlefield instead.
- Salem: George Sibley tries to get a message out indicating that his wife is a witch... by stabbing himself in the thigh and writing on a small piece of paper with his blood. Too bad he gets caught with it anyway.
- Terminator: 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.
- 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. Note that he includes all of these things on the list.
Bert: He's improving. Last time he used spaghetti sauce.
- Premier episode, where a woman clawed a vital clue into the floorboards.
- In "Sherlock Special The Abominable Bride", the Bride leaves the word "YOU" written in blood at the scene of her crimes.
- Starsky & 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.
- An episode of season 6 has Sam draw a devil's trap (which does Exactly What It Says on the Tin) in his own blood for lack of any other medium.
- Rather than just write it down, the King of Hell Crowley burns a clue into the Winchester's table with hellfire.
- The angel banishing sigil is an aversion of this trope, as it has to be drawn in blood or it doesn't work. In a season 6 episode, however, Castiel draws an anti-angel ward in his own blood while he's injured and in a hurry. Since spray paint is later established to be sufficient for similar warding, it's unlikely the blood was necessary, but simply the quickest thing to hand.
- In a season 9 episode, demons wanting to leave an intimidating message key it into the side of the Impala. Dean is not pleased. What makes it worse is that the message isn't even for the Winchesters, it's for Crowley.
- 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.
- 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.
- 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.
- Used to oddly-heartwarming effect in Season 4. After the prison is overrun and everyone is separated, Maggie leaves notes, scrawled on walls in the blood of walkers, to tell Glenn where she's going. The smile on his face when he finds it is priceless.
- The opening episode of Season 4 of The X-Files had X, Mulder's then-informant writing a message in blood on Mulder's doorstep, having been shot trying to bring information.
- 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 rumor 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.
- There's a power that Harrowed have in Deadlands that lets them create spontaneous writing on any surface. The precise effects vary, but making it look scrawled ever-fresh blood is one of them.
- The German musical Mozart! represents Mozart's genius with a child staying by the actual Mozart's side throughout the play, invisible to everyone else. In the song "[[http://www.youtube.com/watch?v=e_jFhGc0drU Wie wird man seinen Schatten los?" ("How do you get rid of your shadow?"), the way this aspect of him is destroying him is driven home when the child stabs him arm with a pen so that he may continue his composing in blood, draining Mozart's life away.
- Due to various props being misplaced in The Play That Goes Wrong, Jonathan (as the Inspector), is unable to find his notebook or pen and is reduced to attempting to take notes on a vase with a key.
- 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: Consistently scattered wherever the markers are. Some prisoners write in blood and... other bodily fluids, while some of the victims go insane with marker-dementia and can no longer write normally with a pen, using their blood in very large letters.
- "Cut off their limbs!" written in blood around the ship. This is how Isaac learns that dismemberment is even more effective than a headshot.
- Portal has loads of insane messages scrawled in... Uh, it's hard to tell what it is actually. According to the webcomic tie-in for the sequel, it's just paint.
- BioShock has a number of messages written in blood, most notably the message on the board of photos reading: "Would You Kindly" In Arcadia, when Andrew Ryan gases Julie Langford in her office, she manages to scrawl the combination of her safe on the window before expiring.
- In System Shock 2, there are walls with bloody messages urging players to REMEMBER CITADEL.
- 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 hellgate) "burn".
- In the Mass Effect 2 DLC Arrival, the wall of a prisoner's cell (with the body of the prisoner still in it) has a drawing of the unmistakable silhouette of a Reaper, in human blood.
- In Wing Commander Prophecy, it's not shown, but in a discussion between some Non Player Characters 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, on the deck.
- At the end of Assassin's Creed I, 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. Although the 'couldn't find a pen' bit is subverted by the fact that a pen was what he actually used to kill himself. He painted the walls with blood because even after being cleaned away, he knew it would still show up in Eagle Vision.
- In the 2013 remake of Leisure Suit Larry, Larry finds a password in the bathroom and writes it down by chewing his fingernail until he bled and scrawling it on a sheet of toilet paper with his blood.
- Rune Factory 4 combines this with Apocalyptic Log using the diary in the attic of the Obsidian Mansion. Made mostly for ambience and as a homage to the horror genre as a whole (including a Shout-Out to Chzo Mythos), since the game is very kid-friendly.
- You'll find bloody messages saying things like "We're doomed" and "God is dead" scrawled on the walls of the stages in Viscera Cleanup Detail. Given that you're a lowly space janitor, you have to clean them off the walls.
- On the penultimate day of One Chance you find that all the other scientists had either killed themselves or were killed by the pathogen, with the exception of one who will kill you or your family if you stayed home the previous day. Among the bodies, you find the word "Sorry" written in blood on a wall.
- At least three times in the Ace Attorney series there have been victims who wrote names, presumably of their killers, in blood. Twice they were incriminating Maya, and both times they were fake. Apollo Justice has a victim writing a number on the floor in his blood, which is then cleaned by his assassin because it was a clue that the victim was an Interpol agent.
- In the case concerning the SL-9 Incident two years before, Neil Marshall apparently wrote Ema's name in blood on a very unusual vase before he died... but then it turned out it was actually Damon Gant, planting false evidence to blackmail Ema's sister Lana.
- There's also the case concerning Maggie Byrde, whose boyfriend wrote her name in the sand next to him with his right hand before he died. He was left handed, and her name is actually spelled "Maggey".
- In the first case of Ace Attorney Investigations: Miles Edgeworth, 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.
- The first case of Dual Destinies contains an example that is both a subversion and a straight example. The defendant's surname is found apparently written by Apollo, who was knocked unconscious, in his own blood. However, the victim of the case had actually written the ID number of her killer, who covered it with a large case; when Apollo found the writing, the killer knocked him out and altered the writing to incriminate the defendant.
- The letter from The Letter is written in blood, and when someone is killed because of the curse, bloody messages appear on the walls near them.
- 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.)
- Mentioned in Freeman's Mind. While walking around some dead soldiers, Gordan thinks to himself it would be funny to write "Latin is a dead language" on the walls with the blood of one of the soldiers, and make it look like he did it as his final act.
- Done in the Zero Punctuation review for Thief: The Dark Project. One of the jokes involves Yahtzee snapping, murdering someone, and scrawling "Press X to Not Die" in the victim's own blood on the wall above the body.
- FUG's calling card in Tower of God after the murder of Edin Dan and Gyetang was to write the organization's name in big bloody letters on the wall.
- Ansem Retort:
- Parodied when the cast plays Pictonary: Axel drew his in Riku's blood for kicks.
- Later, an ominous message is written in blood on the wall. Marluxia ignores the message in favor of complaining about how everyone writes their messages on the wall and how he always has to clean it up.
- The introduction of the girls in College Roomies from Hell!!! 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). As a result of this, when Mike knocks on their door a few hours later, the girls attack in perceived self defense and end up hospitalizing him.
- 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.
- Gamzee Makara has a really fricking creepy variant. Apparently, after he kills off the rest of the trolls, he is going to paint pictures on the walls with their blood.
- It's pretty impressive to be creepy even by the standards of this trope.
- When Aradiabot shows the trolls who wrote the First Guardian genetic sequence on the walls of their rooms, you can see a wide variety of alternative media and substances in use. Plushie guts, troll blood in various colors, sopor slime...
- Back on Alternia, Nepeta kept an extensive wall painting of all possible romantic pairings between her friends, which she would routinely update, painted in various shades of animal blood. Her theme song is actually called "Walls covered in blood", and is considerably more upbeat than you'd expect.
- In Juathuur, Rowasu uses blood at the end of chapter 11.
- A particularly awesome moment in Kagerou has Dark, bleeding from his eye sockets, writing the names of Red's victims in blood, as well as revealing Red's true name, James Valentine Beethoven.
- A nanotechnology reservoir in Last Res0rt is hidden behind a door with some warning scrawled in blood in an alien language.
- In Schlock Mercenary, Kevyn Andreyasn uses his blood to write a warning for Captain Tagon, about his antimatter grenade epaulet being armed, as the same injuries that gave him blood to write with also prevented him from being able to speak.
- 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.
- Done by Bruno the Bandit in a parody of The Da Vinci Code.
- Played for laughs in Bloody Urban, and is apparently the favoured advertising medium of the Australian Liberal Party.
- At the beginning of the interactive comic Deep Rise the protagonist wants to write down their dream before they forget, but can't find any writing implements, so the audience suggests carving notes into their arm with their beak. Of course then they need to find a lighter to burn the blood before it metastasizes.
- The Nostalgia Critic, after the It review, slits his wrists in his bathroom and, using his blood, writes the word "Balloons" on the wall. He's fine by the next episode, though.
- In the MS Paint Adventures fan adventure The White Depths, a cleric blesses a weapon by writing runes on it, but has nothing handy but his own blood. It's just as well though, since one's blood is the best vector for a cleric to channel his magic.
- Played literally in To Boldly Flee, where it's revealed that The Nostalgia Critic wrote Ma-Ti's will after his death using Ma-Ti's own blood. He blames Film Brain for not having a pen on him at the time.
- SCP Foundation:
- SCP-012 is an unfinished composition that Brown Notes you into trying to finish it this way, until you either bleed to death or kill yourself in despair of not being able to complete it. SCP - Containment Breach includes it as one of the many things that can kill your character if you're not careful, complete with hearing the tune in his head as he bleeds himself to death.
- SCP-140, an unfinished book of a demonic ancient civilization which retcons that race into history as it is written in, apparently prefers blood as a medium.
- The Simpsons
- In "Principal Charming", Bart wrote his name in the schoolyard using grass-killing chemicals.
Bart: Maybe it was one of the other Barts that—
Skinner: There are no other Barts!
- In "Cape Feare", Sideshow Bob writes death threats to Bart in blood. And his diary. And amusing letters to Reader's Digest. He faints midway through one of the latter.
Snake: Use a pen, Sideshow Bob!
- 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.
- A non-bloody example: 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!) 
- In "Kiss Kiss, Bang Bangalore", noted MacGyver fans Patty and Selma kidnap MacGyver star Richard Dean Anderson after he'd dismissed the show as merely "a paycheck" and liked Stargate SG-1 more. After Anderson escapes, Patty and Selma say "we'll always have what he wrote", pointing to a message for help. Patty asks "What did he write that in?", and Selma answers "Grape juice and tears."
- In "Principal Charming", Bart wrote his name in the schoolyard using grass-killing chemicals.
- Celebrity Deathmatch: At the beginning of the Macaulay Culkin vs. Haley Joel Osment match, referee Mills Lane asks Macaulay for an autograph for his grandson. Macaulay asks for a pen, but Mills doesn't have one on him. Macaulay then bites off his own pinkie finger, and signs his autograph in blood.
- In the Family Guy episode "A Fistful of Meg", Meg hires a bunch of jocks to beat up a bully who threatened to kill her. Later, she finds their bruised corpses with the message "YOU'RE NEXT, MEG" written on the wall in their blood.
- Played for Laughs in OK K.O.! Let's Be Heroes, when the characters make a movie. Enid is murdered, and writes the killer's name "in her own ketchup!" (Movie!Rad, reading it upside-down, then goes to find out who "O.K." is.)
- 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 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.
- During the 1937 massacre by police of Nationalist protesters in Ponce, Puerto Rico, a young man named Bolívar Márquez dragged himself to the wall of Damas Hospital after being shot and wrote "¡Viva la República! ¡Abajo los asesinos!" ("Long live the Republic! Down with the murderers!") in his blood.
- 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 − despite the victim being a French teacher.) 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.
- Parenthetical Girls are hand-numbering their latest album in their own blood.
- A man in Pinellas, Florida tried to invoke this trope after murdering his girlfriend by writing the first name of his victim's ex-boyfriend on the wall in her blood, creating the impression that she wrote her killer's name as she died. His ruse failed when the police took a closer look at the victim's injuries and realized that she would've been physically incapable of pulling it off, not to mention the blood was on her right hand and she was left-handed.
- 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.
- Clive Barker once pulled it off in real life, albeit inadvertently. Chuck Palahniuk related a story where a teenage fan of Clive's waited in line at a book signing, then when he reached the front of the line, immediately cried "Clive, this is for you!" and slashed his own wrists with a razor blade. Barker grabbed the kids' wrists and slammed them down against the books he'd left on the table, keeping the pressure on the wound long enough for paramedics to arrive and save the kid's life, then dutifully autographed the requested books in the kid's blood and delivered them to the kid in the hospital.
- 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.
- Anthony H. Wilson, head honcho of Factory Records, had several contracts (most notably that of Joy Division) written in his own blood - not for want of a pen, but because he was batshit insane.
- Sergey Yesenin, one of the best Russian poets of the early 20th century, wrote his last poem Goodbye, my friend in blood. He complained to a friend that day: "This mangy hotel has no ink. I had to write with blood," and showed 3 shallow cuts on his wrist. Yesenin was very depressed (therapy didn't help) and hanged himself the next day, it's possible that he started to slit his wrists, but changed his mind and wrote the poem instead. A series of copycat suicides followed with crappy poetry written in blood.
- The "Dear Boss" letter allegedly sent by Jack the Ripper claims that the killer "saved some of the proper red stuff" from a previous murder to write the next one with, "but it went thick with glue and [he] couldn't use it." (It's worth noting that most historians consider this letter to be a hoax.)
- U.S. Army Counterintelligence officer Ib Melchior (yes that guy) had the wife of a Gestapo official hang herself in her cell in the belief that she'd be tortured for the location of her husband. She also bit open her wrist and wrote a farewell to her husband in blood. While shocked, Melchior realised that she wouldn't go to such lengths unless she was sure her husband would receive her final message. So he hauled her traveling companion into the cell to view the dead body. She broke down and confessed to being the sister of the Gestapo official, whom they planned to meet up with later on.
- A brainteaser: Dr. Lax is murdered in his office. There are five suspects, Gerry, Julie, Jason, Sofia, and Brian. The one clue is a calendar with the numbers 6, 4, 9, 10, and 11 written on it in blood. Who is the killer? Solution: At first it seems like a number to letter puzzle, but that would spell out "FDIJK", which is gibberish. The clue indicates writing on a calendar, and if each number is assigned to the corresponding month and the first letter of each month written as a word, the killer is revealed to be Jason.