The spark that ignited his own latent desires came from just a single sight. And it had led him down this path. At that given point, Zavier was very much like a pervert who was infringing on another couple's private moment. Even then, he was totally unaware of his own throbbing erection.
Zavier took in the live action with devouring eyes, not even peeling his eyes away even for a second. He was as heavily invested in this couple's fucking spree as the couples themselves. They unsuspecting couple didn't know that they were unwillingly partaking in a threesome, only the non-contact kind. Zavier hadn't planned for this at all. He had simply been on his way, and fate led him to this. It didn't mean he wasn't going to enjoy it thoroughly. And that he did.