Watchtower (2002)

Orphan Mike O'Conner was abused from age three by his own dad, fled to Chicago to start a rock band but got dragged in bad mates' crime and convicted under probation. Mike's sister, Kate, managed to get him released and employed as assistant lighthouse guard under Adam Terrell, an author on sabbatical. However, Adam is murdered by serial killer Art Stoner, who takes Adam's place and identity. Art himself is the traumatized son of a prostitute, abandoned by the father, who had to watch his mother 'working' and got beaten, as if responsible, whenever her 'clients' hit her. 'Adam' seems to work out as Mike's substitute father, smacking him at worst, but their past starts catching up and Art being seen in action as Kate's lover poisons the triangle dramatically.