After a tragic incident results in the death of his father, Esteban Diaz, and the police officer who took his life, Sean is forced to run away from his home in Seattle with his younger brother, Daniel Diaz. In fear of the police, he intends to reach their father's hometown of Puerto Lobos, Mexico, all while attempting to conceal the emergence of Daniel's mysterious supernatural power.
He is voiced by Gonzalo Martin.
During "Roads", Sean has short, cropped dark brown hair and wears a maroon beanie with a yellow logo on its rim (while walking home from school). He wears a grayish-blue zipper pocket hoodie with a "WOLF SQUAD" logo over a white T-shirt, coupling this with grey khakis and a reddish-brown belt with its strap hanging out from underneath his hoodie. On his feet, he wears grey running shoes with blue laces and green markings.
By "Rules", and during The Awesome Adventures of Captain Spirit, Sean's hair has noticeably grown - his formerly short bangs now reaching his mid-forehead. While in the Willamette National Forest, he wears a brown fleece-lined denim jacket over his hoodie. During Captain Spirit, he wears a light orange quarter-zip pullover over a tan zip-up hoodie. His khakis have begun to develop holes at the mid-thighs and kneecaps, and he now wears sturdy brown hiking boots. After spending some time at his grandparents' house, there is a blue patch sewed onto his pants.
LiS2E3 Wastelands - Sean's Pajama T-Shirt
Sean's recursive t-shirt graphic in Episode 3.
During the opening flashback in "Wastelands", Sean wears a grey t-shirt with a logo reading "NYC-UK" alongside orange boxers and white socks. In the present day, Sean's hair has grown further, his bangs now almost touching his eyebrows; optionally, Sean can have his hair cut by Finn, resulting in a mohawk. He still wears his "WOLF SQUAD" hoodie, which shows several signs of wear; multiple holes have developed in the fabric, the logo has several cracks, and the collar has been ripped and stitched back together. A patch depicting what appears to be the Sigil of Baphomet is sewn onto his right shoulder. His grey khakis now have more patches, including one that reads "SPACE FUCKUPS" on his back pocket and another depicting a skull embedded with knives. While in his tent, Sean wears a grey graphic t-shirt, green boxers depicting tadpoles and a frog alongside the word "HI!", and dirty white socks. Optionally, Sean can get a tattoo of a wolf or three marijuana plants done on his right arm by Cassidy.
During "Faith", Sean's hair has been shaved to a buzzcut, as well as having a bandage over his damaged eye that left him half-blind. During his time in Sacred Hope Hospital, Sean wears green hospital garbs and white socks. When he escapes the hospital, Sean wears his recovered clothes. While walking to Havens' Point, Sean has his hoodie in his backpack to show his grey graphic t-shirt, as well as being partly sunburnt. After being picked up by Karen and having a shower, Sean wears his khakis with a clean white t-shirt and red boxers with blue whales on them. While infiltrating the church, Sean puts his hoodie back on, as well as wearing a black eyepatch provided by his mother. He also wears a multicolored bracelet on his right wrist.
During "Wolves", Sean's hair has grown back to a stage that is slightly shorter than in the episode "Rules", but still longer than in the episode "Roads". He briefly does not wear his signature hoodie in favor of a dark grey and brownish baseball T-shirt and sports a grey bandana with light brown detailing hanging loosely around his neck to mid-torso area, but still retains his patched up grey khakis and hiking boots.
Sean has the option of decorating his backpack with souvenirs he finds along his journey. Throughout most of "Roads", Sean wears a grey school bag which is adorned with patches displaying a mosquito, the word "NSFW" appearing as if on fire, and a smiling doodle. At the beach, Brody Holloway gives Sean a faded green-and-red hiking backpack which features an "ULTRA-D" logo, the phrase "All who wander are not lost", and several hobo signs are written in black marker.
Sean is described as "creative, sensitive and protective" in official marketing material.
Sean's creative side is shown by making drawings in a sketchbook his father had purchased, who seems to have encouraged Sean to draw.
His protective side is shown when Daniel is getting harassed by their neighbor, Brett Foster, for spilling zombie blood on his shirt. Sean can defend his little brother and attacks their neighbor for cruelly insulting them. After he runs away from home with Daniel, he becomes more protective of him on their journey to Puerto Lobos.
Sean and Daniel are seen briefly in the ending of the game, standing on the other side of the fence. The brothers wave hello to Chris Eriksen after he gets up from the ground.
- Sean's zodiac sign is Leo.
- Sean is described as a typical teenager by Scriptwriter Jean-Luc Cano.
- The Diaz brothers are confirmed to be half-Mexican with Mexican descent on their father's side.
- As of "Rules", they are implied to be at least partially Irish on their mother's side.
- In the reveal trailer, the newspaper snippet seen stated Sean's age as 17.
- Sean's middle name, "Eduardo", may be a reference to Lead Artist Edouard Caplain.
- Sean's voice actor, Gonzalo Martin, improvised Sean calling Daniel "enano", which was inspired by how Gonzalo called his own younger foster brothers.
- Sean uses the Spanish term "tipo" when referring to a guy. The term "guey" exists in Mexican Spanish.
- Sean learned how to use a washing machine when he was "about eight", which is approximately the age he would have been when Karen left the family.
- The option for Sean to call himself El Diazblo Loco (meaning "The crazy devil" with a pun on his last name, Diaz) is a reference to a text message Esteban sent him on October 11, 2016, where he says they could make a great team, "Los Diazblos Locos!"
- Sean can tell Brody that he's only ever lived in one place, however, when examining his house keys at the beginning of the game, Sean will say he's lived there for only ten years. He could either be lying to Brody or instead mean he's always lived in Seattle.
- Depending on the player choice, the only crime Sean is wanted for is the murder of Kindred Matthews; however, if Sean steals the camping gear from Bear Station, Claire will inform him upon their meeting that he is wanted for the assault of Hank Stamper and robbery. (Including the camping gear and raccoon hoodie, Sean can steal up to $150.37 worth of goods.)
- During Episode 3's opening flashback, Sean wears a t-shirt which bears the same brand logo as a shirt worn by Max Caulfield during Episode 2 of Life is Strange. Another resemblance between the two's clothing is that they both wear a piece of clothing with a picture of their respective spirit animal on it in earlier episodes, those being Max's doe shirt and Sean's wolf hoodie.
- Sean's sexuality is addressed in Episode 3, where he is able to enter romantic relationships with both Cassidy and Finn. He is given the option between saying some boys are cute and liking girls more during the episode's campfire sequence. Although Sean seems heterosexual at first (with his mentioned crush Jenn Murphy in Episode 1), his sexual identity has not been directly identified in the game (as in real life, there are bisexuals who can lean more towards one sex while still being attracted to another).
- Sean is a fairly good student, as shown by his 3.5 GPA.
- Sean likes burgers with double cheese and dislikes onion.
- In Episode 3 and 4, Sean is seen wearing a top that may be referencing the famous Photoshopped continuation of the Ryan Gosling and Macaulay Culkin T-shirt saga of 2014. This continuation effect is known as the Droste Effect or Mise en abyme, where a picture appears within itself where a smaller picture would be expected. This can create the appearance of an infinite loop that goes beyond the visual bounds.