True, haha. Vail and Sylvia already know each other and are sort of family friends. If Victoria hadn't come along, she's the one Vail would have eventually married, because their two clans had been considering forming a union for some time. He gets along with her well enough, but they don't have any romantic chemistry, which is why he was never interested in pursuing her before.
I'm thinking that later on in the story, Sylvia could become a more major player. Not as a love interest, but as a potential ally and/or friend since she isn't particularly interested in marrying Vail either. She isn't opposed to the marriage (since they're already friends, he's not the worst option for a husband to her), but she's definitely indifferent at best. After the Wynters take over London, she would want to help Vail and the rest of the Hygraces get back on their feet to retake their place at the top of the food chain because they were better leaders than the Wynters would ever be.