Is it alright if you do the supernatural au where Tim is a gargoyle and Buster cant be affected by magic? That au.
1. Living with Buster is a huge pain in the ass. Tim doesn't have a specific magical talent, but he's a magical being and he can use minor spells and magical talismans, except now that he's living with a Null he can't and so he has to do shit like take aspirin instead of using a headache banishing spell and so on. It gets old.
2. Buster knows he shouldn't encourage it, but he loves to watch Tim fly. As a Gargoyle, Tim's slim and sort of sand/buff colored, but wings are darker and a little redder than the rest of him and they're bigger that Buster would have expected. Sure, his clawed feet freaked Buster out at first, but when he flies, he's all grace and power and Buster can't take his eyes off him.
3. Buster's family is fine with the magic, but they're a little taken aback when Buster admits he's involved with a Gargoyle. They don't disown Buster or anything like that, and they're always polite when they visit SF, but Buster doesn't bring Tim home for several years. Chris Lincecum's sole objection to the relationship is that he doesn't think being involved with his catcher is good for Tim. Tim's mom tells Tim that she's not sure if Buster really knows what he's getting into.
4. Buster loves the way Tim looks when he flies, but at first he's a little nervous about having sex with Tim when Tim's in his Gargoyle shape. He doesn't want it to be a huge thing, because he really does think of Tim as more than a casual hookup and he thinks he might even love him, but Tim's got claws on his hands and feet, and hooks on his wings and also, his elbows are kinda bony. Tim's just as nervous because he doesn't want it to be this big test of Buster's intentions and also, he doesn't want to hurt Buster. So the first time they try it, Buster lies on his back and Tim sort of crouches over him and Buster's totally shocked because Tim looks dangerous and a little scary and that turns out to be a huge fucking turn on.
5. They talk about kids and eventually, when Tim retires, they stop using birth control. Carrying a baby means that Tim has to stay in his Gargoyle shape the whole time, which is kind of a pain, but overall Tim deals with it pretty well. They have a boy and then, a few years later, a girl but after that, Tim says he's done. Both kids can change into Gargoyles and they're kind of a handful, but Buster and Tim turn out to be pretty good dads.