The protagonist of D4. David was once a narc for the Boston Police Department, but quit the force after his wife ("Little" Peggy Young) was murdered in front of him. He has no memory of the incident except for Peggy's last words: "Look for D". He has the power to revisit the past using special items called "mementos", allowing him to inspect crime scenes before they happen and solve cases that would otherwise be unsolvable. His goal is to change history by finding a memento that will let him meet Peggy and save her life.
Season 1 reveals that David had been working undercover at the time of Peggy's murder, having successfully infiltrated a drug ring linked to the distributor of "Real Blood".
- Batter Up!: David against Rabbit. Memorabilia in David's room shows he used to be a baseball champion.
- Character Tics: David is constantly seen chewing strawberry-flavored gum, something he's picked up from Little Peggy.
- Cloudcuckoolander: Maybe not quite as much as another one of SWERY's detective protagonists, but it's there. Highlights include pretending to make his hot dogs walk at the dinner table and waving around a foam finger on an airplane, completely straight-faced at that.
- Forgets to Eat: Kaysen frequently comes over to cook for him since he'll just subsist on beer otherwise. Then again, even during the meal cutscenes, David usually plays with his food instead of eating it.
- Heartbroken Badass: David's acrobatics help him maneuver through multiple fights.
- Improvised Weapon: Uses one of Sukey's legs against Rabbit.
- Occult Detective: Although there isn't many paranormal events going on, David uses his power to solve mundane crimes by using mementos.
- Trademark Favorite Food: David loves tequila.
"Little" Peggy Young (nee Oldmann)
David's late wife. She was murdered two years previously, found in their bathroom with all of the blood drained from her body. Her autopsy revealed trace elements of a compound similar to that of "Real Blood", but she ultimately tested negative for the drug. She suffered from an unspecified illness that caused her to bleed uncontrollably, and had begun to relapse just before her murder. She was also pregnant with David's child at the time.
- Innocent Blue Eyes: Much focus is cast on her bright blue eyes, and David often fondly remembers how innocent and pure she was as a person.
- Ill Girl
- The Lost Lenore: David is unable to move on from her death, holding on to the hope that his powers will allow him to change the past so that she will live again.
- Posthumous Character: David is often seening visions of her, usually as memories he is reliving.
- The Teetotaler: David notices that all the time he knew her, she always abstained from drinking.
Forrest "Teddy" Kaysen
David's former partner at the BPD, who often comes by his place to help him in his investigations as well as to have a meal. He is heavily involved in the BPD's investigation into "Real Blood". Unknown to David, he has been secretly meeting with Dr. August Oldmann, one of Peggy's adopted fathers.
- Big Eater: Forrest regularly eats enough food for five people. His culinary feats include eating five steaks on top of each other, five slices of pizza at once, several gallons of chowder, and a pint glass full of oysters and lemon juice... with minimal chewing.
- Friend on the Force: For David.
- Reused Character Design: The character of Forrest Kaysen is a recurring element in SWERY games. Time will tell whether or not he's a villain like the other Kaysens.
- Supreme Chef: His cooking looks great, taste great, and in big portions too. In fact every time David asks for Forrest to cook, the food will refill David's stamina meter completely.
A freeloader in David's house who occasionally does the shopping around the place. Although she appears to the audience as a human woman, she acts like a cat and all the characters in-game treat her as if she was one. She also acts as the in-game shop.
- Cat Girl: A weird subversion of this trope. She doesn't wear ears or a tail, but she meows, loves to climb on furniture, and catches animals in her mouth. In Memento segments, Amanda appears as an actual white cat.
- Maybe Magic, Maybe Mundane: It is implied that her appearance is the result of David's head injury causing him to hallucinate that his cat is a human, but that still doesn't explain why Amanda is apparently capable of buying groceries.
- Ms. Fanservice: Wears a leotard that shows off her backside and isn't afraid of strutting her stuff. Though she does a mean Michael Jackson impression too.
Antonio "Rabbit" Zapatero
A courier for the drug "Real Blood". He asks the DEA to be brought into protective custody in exchange for offering information on his supplier, a mysterious drug lord whose name begins with a "D".
- Glass Eye: His left eye is a prosthetic that David knocks out and is able to use to travel back in time.
- Hot-Blooded: Aggressive, cocky, and rather loud and chatty during his brawl with David on the plane.
- No Celebrities Were Harmed: Looks just like Benicio Del Toro.
- Sir Swears-a-Lot: Every second word he says is a variation of F-bomb.
A stewardess aboard the flight carrying Zapatero. She has an uncanny resemblance to the late Peggy Young. In Episode 2, it is revealed that she is actually an undercover DEA operative.
- Ascended Fangirl: She became a DEA agent because of her unabashed love of James Bond films.
- Identical Stranger: David often confuses her for his late wife due to their resemblance down to the birthmarks under her left eye (though Olivia has three where Peggy had two).
- Only Sane Man: Is appropriately suspicious of David, considering he technically is a stowaway
- Suspiciously Specific Denial: Olivia constantly refuses to admit she needs help, and she definitely doesn't need you to find something random on the plane.
A mysterious figure in a white labcoat. He is incredibly tall and speaks verrrrrrrrrrrry slooooooooowly.
- Ambiguously Evil: He has a rather menacing, creepy air to him, and David says that his bullet injury aches whenever he sees him. But when David converses with him, he actually helps David realize the situation he's in, along with being polite about the whole thing.
- Ambiguously Human: On top of everything else, he can travel through time and is seemingly invisible to everyone but David.
- Creepy Monotone
- Expy: Of the Giant from Twin Peaks, being a tall, strange man who speaks in a slow manner and is Invisible to Normals.
- Leitmotif: "Arousal" tends to play whenever he appears.
- Noodle People: He's abnormally tall and gangly in comparison to other characters, to the point where he has to tilt his head to stand up on the airplane.
- Scary Black Man: Albeit a more... unsettling example than most.
- Verbal Tic: He talks in a ridiculously slow manner, drawing out every single syllable in a word.
The US Marshal in charge of transporting Zapatero. He seems to have a grudge against David. He lost his wife and daughter to a "Real Blood" incident and has been feverishly pursuing "Real Blood" cases ever since. When lightning strikes the aircraft, he uses the confusion to take Zapatero into the lower decks and torture him for information on "D". However, he is impaled by an electrical wire controlled by DELTA and killed.
- Bald of Awesome: He claims that he shaved his head.
- Berserk Button: He's very sensitive when it comes to his family, because he's a Crusading Widower.
- Roaring Rampage of Revenge: David confronts Derek with his inference that the latter is after Rabbit's boss because he's on one of these for his family. Derek doesn't deny it.
- Shadow Archetype: To David. Both lost their family due to Real Blood. While David left the police to conduct his own investigation, Derek remained a Marshall to keep close to the Real Blood case. Furthermore, Dererk doesn't believe the past can be changed and is more eager for revenge than justice.
A rather paranoid and obsessive-compulsive passenger aboard the plane.
- Big "WHAT?!": Basically her catchphrase.
- The Cuckoolander Was Right: She turns out to be correct in her prediction that the plane would get hit by lightning. David lets slip that the return flight is headed for disaster when they meet for the second (her first) time.
- Jerkass: Doesn't hesitate to berate or lash out at anyone who insinuates she isn't Properly Paranoid.
- Lady Swears-a-Lot
- Nervous Wreck
Duncan (& Sukey)
A camp fashion designer who is never seen without his beloved, a mannequin named Sukey.
- Camp Straight: Sort of.
- Cloudcuckoo Lander: Probably the most bizarre one in the cast, given his fixation on strange fashion and his insistence that Sukey is "alive".
- Companion Cube: Sukey.
- Consulting Mr Puppet: Again, Duncan toward Sukey.
- The Fashionista
- Insistent Terminology: His companion is not a mannequin, she's Sukey.
- You Gotta Have Blue Hair: Green in his case.
A steward on the plane. He has a habit of using an inhaler to calm his nerves and maintain his professional demeanour. In Episode 2, it is revealed that he is an undercover DEA agent working alongside Olivia. However, he goes rogue and uses Real Blood to unleash his true identity: DELTA, a superpowered killer with the ability to generate and control electricity at will.
Dr. August Oldmann
One of Peggy Young's two foster fathers. A mysterious man who was the first person on the scene of Peggy's murder. He has been secretly meeting with Forrest Kaysen.