When a rite call for your blood, where do you cut? Right across your palm, of course.
You rarely use your hand anyway, right? That's not an inconvenient place to have an injury. There certainly aren't any sensitive muscles or tendons there. Not an area packed full of pain receptors or anything.
The Doylist reason for this trope is basically that it's the easiest kind of wound to fake.
- One can hide a packet of fake blood in one's hand to cut — and if one needs a lot of blood, one can hide the tubing up their sleeve.
- If one needs a close-up, a cut in the palm of a latex glove is easier to fake than a cut on the back or finger.
- If one needs to avoid close-ups, it's easier to keep the palm of one's hand out of view of the camera than the back or a finger.
Aside from all that, one has to consider the gravitas of the scene. Are there more practical body parts to nick for a bit of blood? Absolutely. Would it look nearly as dramatic or badass holding those body parts over some mystical chalice? Probably not.
- In Attack on Titan, Eren does this by biting into his palm, in order to transform into a titan. This is eventually further expounded later on in the story.
- In Naruto, people who need their own blood to cast jutsu will often cut/bite their fingertips instead.
- In Princess Tutu, Fakir revives Mytho's Cool Sword by cutting his hand, and pouring the blood from the wound into a fountain, and reciting a spell in Gratuitous German while dipping the blade into the bloody water.
- Subverted in Runaways. Nico's spell casting is done through The Staff Of One, which only emerges from her soul when blood is shed. The first time she actively attempts to summon it, she tries this. And she hates it. She would go on to come up with creative ways to shed blood that didn't involve cutting, from averting No Periods, Period to brushing her teeth until her gums bled.
- In Death: The Time of Your Life, blood from a cut palm is used to power a spell to send the characters to the land of the dead and come back alive.
- No less than three times in Heart of Ashes, a palm is cut and blood dropped on someone else during a magic ritual. In the first chapter, Fankil does this to resurrect the recently perished Kathryn. In the same chapter, Andraya does this to awaken from deathlike coma Smaug (who has recently survived his canon death and transformed into a man) at the cost of her fertility. The third time occurs during the climax when Fankil tries to fulfill the purpose he resurrected Kathryn for: locating the Door of Night through her influenced vision so that he can free his father Morgoth from the void.
- The Rigel Black Chronicles: Not wanting Rigel's wand associated with her real identity, Harry instead identifies herself to the goblins by holding out her hand and having one slice it with a spear to take a blood sample.
- The Ultimate Evil:
- When Shendu is bound to his Other Valerie Payne in the rewritten reality, they slash each other's left palm and drink each other's blood. Their union leaves for them both a permanent scar on the slashed palm that endures the restoration of reality.
- In the sequel, Hsi Wu uses his claw to cut out a piece from his right palm and sends it into Jade in order to merge with her.
- Drago uses his talon at one point to pierce his palm in order to use his blood in a spell.
- In The 100 fic “Twisted Steel”, it is noted that traditionally swearing in a new member of a clan in Triku culture would involve the new member cutting their palm as a way of showing that they would be willing to shed blood for their clan. Since Clarke lost both her arms in an accident on the Ark and has a pair of Artificial Limbs instead, she and Anya decide that they can do the usual ritual using shoulders instead (Clarke's left arm was completely severed while her right was only severed at the forearm), due to the unconventional circumstances.
- The Road to El Dorado: The wicked high priest Tzekel-Kan slices his palm to smear blood upon a stone relief of one of the two founding gods of El Dorado. He does this to emphasize that he has seen through Tulio and Miguel's masquerade. "Gods. Don't. Bleed."
- In the film The Brother from Another Planet, the protagonist uses a shard of glass to cut his palm in order to use his blood to write a message on a graffiti-covered wall. However, it's no big deal to him, as he is an alien who heals easily and quickly.
- Done in Deep Blue Sea when blood is needed to attract the sharks' attention.
- In The Hangover, Alan tries this to start a blood pact, freaking out everyone else.
- In Hellraiser, Larry cuts his hand on a nail and drips blood on the attic floor. Underneath lie the hidden remnants of Frank's body which the blood partially restores back to life and consciousness.
- The Client does this to both himself and Jay in Kill List while Jay is signing a contract.
- In the extended version of The Lord of the Rings: The Two Towers one of the Wild Men of Dunland swears fealty to Saruman. When asked to prove it, he slices his palm open and says that they will die for Saruman.
- In National Treasure, Ben cuts his palm then presses it to the handle of the carved pipe they've found, so they can press the bloody pipe on a piece of paper and see what the words on it are. He couldn't find ink in the arctic.
- Done twice in Pirates of the Caribbean: The Curse of the Black Pearl, when blood is needed to break the curse. The first time, Barbossa does it to Elizabeth. Will does it to himself the second time, having to hurry things along before Barbossa killed either Elizabeth or Jack, who had just done it himself before throwing the medallion to Will.
- In Practical Magic, Sally and Gillian slice their palms and clasp hands to cure Gillian's Demonic Possession. It also conveniently works as a Curse Escape Clause.
- Robin Hood: Prince of Thieves has Robin slice open his palm during his oath to avenge his father, then he wraps it with a rag and continues battling for the rest of the film seemingly without pain or disability.
- At the beginning of Rob Roy Rob Roy is challenged to a friendly duel to the first cut but doesn't feel like participating, so he purposely slices his palm on the other guy's sword in order to lose. This becomes a Chekhov's Gun when in the climactic duel he grabs the other guy's sword with his bare hand in order to take it out of play.
- In Star Trek: Nemesis, Shinzon cuts open his palm to provide a blood sample for our heroes. It reveals that he's a clone of Captain Picard.
- In Aztec, Chimali's signature is the slap of his bloodied hand. This appears as a recurring theme throughout the novel. It's fitting, because Chimali becomes Mixtli's sworn enemy, and whenever he's done evil to Mixtli's loved ones, he leaves a handprint where Mixtli can find it.
- Mirai from Beyond the Boundary crosses this over with Wound That Will Not Heal: her main offensive power is manipulating her blood to form weapons and the like, and her source of blood is her palm. Her hand is almost always in a bandage to cover it up.
- In The Bishop's Heir, Kelson recalls the day he and Dhugal became foster brothers. Each of them used the other's dagger to slice open a palm, then they clasped their wounded hands together and Dhugal bound them with a handkerchief before they swore their oaths. Years later, they both retain faint scars across their palms.
- In Andre Norton's Dread Companion, Kilda has to bleed to get the grass that can act as a guide. She even has to pull it by the bleeding hand.
- Egil's Saga: When Egil uses magic to check a horn of ale offered to him by Atloy-Bard for poison, he carves runes into the horn and "stabs the palm of his hand" in order to smear the runes with his own blood.
- Zig-zagged in Harry Potter and the Half-Blood Prince when Harry and Dumbledore encounter a door that requires a blood sacrifice. Upon entering, Dumbledore cuts his hand — but it happens to be the hand that is dead from a curse, so it's not as inconvenient as it normally would've been. When they leave again, Harry uses blood from the palm of his hand — which he had accidentally scraped on a rock earlier.
- In Mercedes Lackey's Heralds of Valdemar series, a mage who has become a reluctant Fisher King does this to mix his blood with the soil when he adds to his territory. Because of his connection to the earth, the cut heals very quickly.
- Casting spells with Wild Magic in The Obsidian Trilogy by Mercedes Lackey and James Mallory requires a blood sacrifice, usually done by a simple nick on the hand. However, in When Darkness Falls Idalia slashes her palm open with a dagger to summon the Starry Hunt to help battle the demons.
- Justified in On Stranger Tides, in which Shandy has to draw blood from his sword-hand's palm to maintain the mystical connection between his blade and his bloodstream.
- Princesses of the Pizza Parlor: From Princesses in the Darkest Depths: For some witchy, Blood Magic:
This was perhaps the witchiest thing she'd ever done [...] she took her personal knife and ran it over the palm of her hand.
- Averted in Sword of Truth. Richard goes for the inside of his elbow instead.
- This is the means Tenskwa-Tawa uses to produce blood — and pain — to work large magics in The Tales of Alvin Maker, and Alvin learns to do the same; for added messianic symbolism, when large quantities of blood are needed, like Tenskwa-Tawa walking onto Lake Michigan to raise a crystal tower inside a tornado, they pierce their feet too.
- Wulfrik regularly does this as his enchanted ship only responds to his blood. On occasion, he does it so hard blood bubbles from between his clenched fingers, but that's entirely normal behavior for Norscans.
- Angel: Happens at least twice:
- Darla cuts her palm when a shaman needs a blood sample for a spell after he is reluctant cut his own palm instead.
- When Angel kidnaps Linwood Murrow to force Wolfram & Hart to help him with a spell to make the demon Sajahn corporeal, the spell requires blood. Lilah takes out a knife and gives the tied-up Linwood and intense stare, causing him some consternation as he assumes she intends to start slicing him up. Instead she slices her own palm and mocks Linwood for his cowardice.
- Buffy the Vampire Slayer: In the finale, Buffy, Faith, and the remaining potentials collectively do this over the Seal of Danzalthar, in order to open the Hellmouth.
- Done at least twice in Babylon 5, by Narn. Once by G'Kar to make a point to Vir, once by Ta'Lon to satisfy a tradition that his sword must draw blood before being sheathed again. Seems to be a Narn thing.
- Boardwalk Empire. Season 5 has Charlie "Lucky" Luciano's Mafia initiation.
- Averted in Season 3 of Evil, struggling writer Dr. Kurt Boggs is given a demonic ritual that will supposedly treat his writers block. The ritual calls for a few drops of blood, but he sensibly cuts the outside of his hand so he can keep typing. Unfortunately, the ritual's effects are temporary and he has to keep performing it over a period of days, and the cuts mount up, until a suspicious patient notices them bleeding through his bandage and begins to suspect they are evidence of Self-Harm and possible Sanity Slippage.
- Game of Thrones.
- Beric Dondarrion does this before challenging Sandor Clegane to Trial by Combat, which seems a foolish thing to do until it causes his sword to burst into flame due to implied Blood Magic. Sandor as it happens is terrified of fire.
- Xaro Xhoan Daxos cuts his hand and shows the blood as part of his oath to stand for Daenerys and her people. He's lying.
- Averted when a teenaged Cersei Lannister consults a witch — she cuts her thumb for the required Blood Magic.
- House of the Dragon: When they marry in Targaryen tradition, Daemon and Rhaenyra cut their palms before holding each other's hands (and they also cut the central tubercle of each other's lips and make a blood mark on each other's foreheads).
- Krypton has Superman's grandfather, Seg-El, opening his grandfather's Fortress of Solitude on Krypton using the blood of an El. It forms the familiar sigil of the House of El.
- In an episode of Law & Order: Criminal Intent, Goren cuts his hand in order to show a suspect is too squeamish about blood to have committed a very bloody crime.
- In one episode of Lie to Me, Cal slices open his hand to show that the guy they are interviewing has a phobia to blood.
- The Magicians episode "Divine Elimination": Margo slices open Elliot's palm to summon Ember using a blood-stone.
- In the The Midnight Club, the supposedly healing ritual perfected by the Paragon (a death cult), involves seven participants each slicing their palm and marking the forehead of the person to be healed. The titular club performs this on Anya, as she is near death, and even share the knife without cleaning it. Spence, who is HIV-Positive, opts out of this particular idiocy and uses his own personal knife, and assures Anya that she cannot be infected by his blood being on her skin alone.
- Star Trek: The Original Series episode "A Private Little War". When Nona uses the Mahko root to heal Kirk, her husband Tyree cuts her hand first so that her blood joins with the root before it's applied to Kirk's wound.
- Supernatural uses this frequently, often to prove that someone is human by showing that they don't have Alien Blood or react to various Kryptonite Factors. Season 3 Episode 9 Malleus Maleficarum has a witch slicing her hand open in the first few minutes. In Season 4 Episode 1 Lazarus Rising, Dean deliberately averts it when given the opportunity, cutting the outside of his forearm instead to leave both hands useable.
- Star Trek: The Next Generation and Star Trek: Deep Space Nine establish this as a Klingon habit. If they're putting on any kind of ceremony, it's a safe bet that shedding some blood this way is going to be part of it.
- In the Season 4 premiere "The Way Of The Warrior", when General Martok arrives on Deep Space Nine, he demands a meeting with Captain Sisko and Major Kira. He then demands that they all prove that they're not Changeling infiltrators, and demonstrates by cutting his own palm and letting a few drops of blood fall onto the tablenote before handing his knife to Sisko. Sisko and Kira follow suit, which satisfies Martok, and they proceed with the meeting. However, it turns out later that "General Martok" WAS a Changeling infiltrator. They'd already figured out a way to fool the test (likely by hiding blood packs inside their bodies), and it was only for show.
- In the Season 7 episode "When It Rains", Captain Sisko and Admiral Ross have been invited to a ceremony where Chancellor Gowron presents a commendation to General Martoknote . After watching both Martok and Gowron cut their palms, Sisko glumly says "We're next." Ross chuckles until he looks over at Sisko and sees he's serious. ("You're kidding.") Cut to the party after the ceremony, and they both have drinks in one hand, and bandages around the other.
Admiral Ross: It still stings.
Captain Sisko: That's what the bloodwine's for.
- V (1983) had a scene where someone approaching La Résistance for help did this to prove they were not a Visitor.
- The Blue Öyster Cult song "Unknown Tongues" is about a Catholic schoolgirl called Margaret, who lies in bed at night contemplating the mysteries of Glossolalia and the Holy Stigmata (i.e.: the voices in her head tell her to self-harm with a razor blade):
And then she took/Her father's razor;
And watched it cut into her palm;
She put her hand up to her mouth
To taste the blood, so holy and warm....
- Ghost's song "Con Clavi Con Dio" includes this as a description of a cult worshipping Satan.
Our conjuration sings infernal psalmsAnd smear the smudge in bleeding palms
- S. J. Tucker's song "Valkyrie Daughter" has this when the soldier makes his deal with the goddess Hel to forfeit his place in Valhalla so that his daughter can go from Niflheim to Valhalla and become a Valkyrie.
The soldier's eyes clouded... But he cut his own palm,
And signed all his honor away.
- Call of Cthulhu campaign Spawn of Azathoth. During a Cthulhu Mythos ritual each participant must cut the palm of his hand and smear the blood over a severed hand, which animates and acts like the planchette of an Ouija board to point out symbols and provide a message.
- Dungeons & Dragons. In module CM1 "Test of the Warlords", the PC's can participate in the ritual of blood sharing with a barbarian chief. They do so by cutting their palms and clasping hands, thus mixing their blood.
- GURPS Illuminati. The sidebar titled "Blood Samples" describes Illuminati initiation procedures that require using the applicant's blood, such as signing a contract, filling a chalice, etc. The accompanying illustration shows a knife cutting the palm of a person's hand.
- You're going to be doing a lot of this in Curse of the Dead Gods, especially on more challenging explorations where you need a ton of gold for the endgame to pay off the Gods of Wonder. Each time you do it, you accumulate more and more corruption, until your hand is glowing bright pink and emitting smoke from all the curses you've got on you.
- Averted in Dawn of War: Soulstorm. Where most units capture points by standing at attention/prayer, the Dark Eldar slash their wrists and hold the bleeding hand up in salute.
- In Destiny 2: Season of the Chosen, this is used as part of a ritual, but not a magical one. As part of an armistice between Empress Caiatl's Cabal and the Guardians, there is meant to be this between Caiatl and Commander Zavala (on behalf of the Guardians), a symbolic gesture, "Let this be the last blood spilt between our people." It only gets as far as Caiatl doing her half before conspirators attempt to assassinate Zavala.
- In Devil May Cry 3: Dante's Awakening, Vergil uses his katana Yamato to slash his palm as a part of the Blood Magic ceremony to break the spell on the Temen-ni-gru tower. In his case, it's doubtful the wound slows him down because he has an innate Healing Factor.
- In Diablo II, The Necromancer has a Curse spell called "Life Tap." According to Flavour Text in the guidebook, he slits his palms to allow Life Energy to flow through them.
- In the teaser trailer for Diablo IV, the doorway to the room where Lilith is summoned is opened by a trigger that requires blood from three people to activate; the blood is given by the people slapping their palms onto small spikes on the floor.
- In the game proper, there are multiple scenes where blood is required for a ritual and your character or an NPC cuts their palm.
- In Dragon Age: Origins, Blood Magic always has the somatic component of cutting the palm. By stabbing it with a dagger.
- In The Elder Scrolls V: Skyrim, at one point a door needs to be opened with the blood of the Dragonborn. They cut the palm of their hand to do so.
- An unintentional version happens in the Dawnguard DLC: The Dragonborn investigates an ancient tomb and, when s/he presses what looks like a button, a spike pops up and pierces their hand, allowing them to open the blood seal keeping Serana entombed.
- The native ceremonies in GreedFall require someone to cut their palm in order to forge a bond with nature and speak to the spirits of the island.
- Mortal Kombat X newcomer Kotal Kahn enters into matches by ritualistically slashing his palm on a sacred, Elder God-empowered blade to grant him their strength. He will make good, immediate use of it.
- In Star Wars: The Old Republic, during the arc of the Sith Inquisitor's story where they're looking for force ghosts to absorb with a ritual, choosing the light-sided option of finishing the ritual with a blood sacrifice has the Inquisitor do this.
- Legio Arcana: In chapter 3, Oded and Ana cut the palms of their hands to invoke a Loa.
- The Weekly Roll: Lampshaded by Trevor who finds an evil cult doing this, wondering why they'd cut themselves in such a way.
- El Goonish Shive: When Edward Verres wants someone to demonstrate a healing spell that doesn't work without an injury to heal, he slices the palm of his hand open.