Re: luka romanov
1. Nope. Luka pretty emphatically doesn't want children. He doesn't even like animals most of the time. He's never wanted pets. He gets all ... pet-ish with Billy sometimes, but that's because Billy is obviously not an actual dog. He may, someday, get a puppy. Maybe. If Billy really, really wanted one.
That said, he does like kids, but he wants to be an uncle, not a father. Just. Nope.
2. Luka is... very concerned with being irrelevant. He's scared of not being enough, especially now that his presence is just so much. He's scared of misusing what he has and ultimately becoming useless or defunct.
And, this sounds horrible, but he's afraid of the weakness in other people, specifically people who are supposed to be better than he is. Taking care of Billy or his friends is one thing, because he can do that, and Billy's his partner, that's his job. But ever having to care for any of his parents terrifies him. Taking care of Steven absolutely tore him up inside.