Billy Loomis is the boyfriend of the protagonist, Sidney Prescott, in the first of the 'Scream' movies. He and his friends live in Woodsboro, California and attend the local school, Woodsboro High.
He comes across as an intense character who may seem to see everything as a joke, yet he rarely laughs. Examples of this include when he almost gets Sidney into trouble after he unexpectedly climbs through her window, and when his friends make jokes about the recent murders. His intensity increases later in the film, when he displays a more threatening and almost aggressive side after a school friend accuses him of the attacks on the town's teenagers.
His love of the Horror genre is evident almost immediately, when he discusses with Sid how watching 'The Exorcist' made him think of their physical relationship, or lack of. This is also the first time he compares something about a film to real life, which we later see is a habit of his and is a trait which defines his actions. We know from the discussion that the couple have been together for two years (prior to the first film), and began their relationship with a passion. Billy goes on to talk about how the intimate side of their relationship faded. He may be interpreted as a patient and caring boyfriend due to his acceptance of Sidney's intimacy issues; however, he is obviously beginning to want more.
Billy becomes a suspect in the murders about a third of the way into the film, when he once again climbs through Sidney's window right after she is attacked by the killer. He drops a cell phone (mobile) and arouses the already spooked Sidney's suspicions. When the police arrive, they arrest Billy, but he is later released after the Sheriff discovers his phone records were clean.
After this, the couple's relationship remains on the rocks for a while. Although Sidney apologises, Billy seems more angered by the lack of physical intimacy in their relationship, and shows an insensitive side to his personality when he implies Sidney should be over her mother's murder. Sidney later apologises for this as well and loses her virginity to Billy in what seems to be a romantic scene.