Early life (1980-1991)
Little is known about Stiles' early life. He was diagnosed with attention deficit disorder at some point in his childhood and was prescribed Adderall to treat it. As a young child, Stiles' mother Claudia was stricken with frontotemporal dementia, and eventually died of the disease while Stiles stood alone at her bedside, since his father was at work. During her illness, Claudia suffered such horrifying delusions that she was under the impression that Stiles was trying to kill her despite the fact that he was only a child worried about his mother. According to the repressed memory Stiles experienced in a flashback, Claudia even attacked Stiles due to her dementia causing her to develop a very strong case of paranoia and dissociation.
Claudia ultimately died in the hospital when young Stiles was visiting with her, and he had to deal with her loss all by himself because his father had stayed late at work to comfort a woman who was dying after being involved in a terrible car accident. At Claudia's funeral, John saw how badly Stiles was mourning his mother's death and assured him that he still had him, and their mutual loss caused Stiles to become incredibly close to John Stilinski to help each other get through Claudia's death together. Afterward, Stiles began to experience anxiety attacks and bouts of sleepwalking, though he eventually grew out of it for a time. He also seemed to be aware of his father's affinity for whiskey, which occasionally went too far, to the point where Sheriff was asked by his fellow employees to cut down on his drinking.
Hogwarts years (1991-current)
Stiles is a lean young man of medium stature who has pale skin, brown hair and honey-brown eyes. He is known for having freckles all over his face, neck, and body, and his hair is usually gelled into a messy style. His choice in clothing leans toward pieces that are comfortable and casual, such as hoodies, flannel button-ups, baseball-style t-shirts, and slim-cut jeans with Vans sneakers. However, he has also been known for wearing active wear during lacrosse and cross-country seasons, such as Under Armour t-shirts and track pants with tennis shoes.
Personality and traits
Stiles' personality is most accurately described as anxious, hyperactive, and curious. He is a notorious bookworm who excels at piecing together clues and figuring out mysteries. Since becoming aware of the magical world, Stiles' social and generalized anxiety has only become worse, because he fears having to deal with the loss of any more of his friends or family as a result of Dark wizards. Because of this anxiety, Stiles can often become so overwhelmed by trauma that he both physically and verbally lashes out at anyone around him, whether they are friend or foe.
Despite Stiles' anxiety and his increasingly violent reactions to bad news, Stiles is a very loyal person who would do anything to protect his loved ones, even if it means giving up his life to do so. Stiles is slow to trust people, but once he warms up to them and the person gains his trust, he becomes very close to them and will do whatever he has to do in order to protect them and ensure their safety.
Stiles, like his father, enjoys puzzles, and acts as the lead investigator to gain information and evidence regarding the threats that they face. For this reason, Stiles' intelligence is his greatest strength, and has either given them an advantage or has saved them in multiple situations throughout their time together.