His motive is usually either his depraved sexuality or an unrequited love, like his Psycho Lesbian sister.
Usually a villainous take on the Camp Gay or, on the other end of the spectrum, a Manly Gay sexual predator whose preferred 'quarry' are straight men or young, naive Twinks.
The Spear Counterpart of the Psycho Lesbian, and the monosexual counterpart to the Depraved Bisexual.