Well, I can't lie and say that Matt wouldn't be physically attracted to him, and not only because he's the demon of lust. A 'love' interest would definitely be interesting! What kind of relationship with your character be looking for? Not a serious, boyfriend-y one, I presume? And that's perfectly fine with me! I'm pretty easy, as well. But I would certainly be willing to have Matt 'work on' his powers, if Big Daddy showed an interest in them. Right now, he honestly doesn't do a whole lot with them, but if Big Daddy found out through a third party somehow that Matt was superhuman, he might be able to inspire him to work on his abilities. Because who knows, they may become useful somehow!
By the way, does he go by Big Daddy and want people to call him that? Because Matt would have a very, very hard time doing that and being serious at first.