Sparks and Smoke by Eve Morton

Greg and Paul have been roommates for the past six months. Greg likes Paul -- probably too much -- and his admiration only grows when Paul's computer sparks and smokes, and he becomes the consummate mechanic to fix it. During a heatwave. While not wearing a shirt.

Paul continues to entice Gregory, even when he's at work, making Greg wonder if there is something he's been missing in his roommate's other interests.