I don't remember if this was the plot of a particular manga that I once read, but anything along the lines will do nicely :3
So a guy(uke) saves the seme from some kind of danger( or thinks he does) such as bullies( haha, always seem to b there) something about to fall on him, about to fall from a height, people holding a strong grudge, rape, ect. And he thinks that he's weak or something, so he tries to protect him( still talking about the uke wanting to protect the SEME)
And at some point he finds out the seme( the one he thought needed to be protected) was really strong and dominant( at least for him ^_^) and ya know, steamy stuff comes next XD
Anyways, thanks for reading!