Part of You by Aiden Bates

That reason to be is out there, waiting for you. But what happens when you aren’t expecting it to fall right into your lap at the worst possible moment? Do you dig in and hide in the shadows? Or do you open up and chance that light burning you alive?
He was ready to give up until fate came asking a favor.
Theo is lost, hopeless, and feels like the world’s gone to pieces. When a co-worker becomes desperate enough to start asking office mates to try to match for an organ donation, Theo has no reason to refuse. When he’s a match, it turns his world upside down. This operation will change his life in more ways than one.
Eli almost died at the hands of his ex. The only thing he wants is to see his little girl grow up, and with Theo’s help, he might just get that chance. When it turns out that his donator can relate to him and his daughter, Eli’s sure this must mean there’s something more between them.