He is a college-aged cousin of Rianne's. In the opening chapters of Wicked Lovely, it's noted Rianne is having a party. Dominic is expected to be there, along with several of his fraternity brothers.

Later, Leslie notes Dominic's parents are away for the week, so the partying will be a daily occurence. Aislinn doesn't attend any of the parties.

Although he's mentioned more than once, Dominic doesn't actually appear in the novel.