UkeEh?Why does everyone say A-kun is the seme...!?Are you hooked on subverting traditional couplings again?R-Right.A big macho guy like that is obviously the uke...!Come on, that's heresy lolOf course the smaller of the two in BL is going to be the uke lolBut when you're having a large breed of dog and a small breed of dog mateyou make the larger breed be the female!SemeIf the smaller breed were the female,both the mating and the pregnancy would be dangerous!It's the same in BL...Having the bigger one not be the uke poses a physical danger...Your head's the only danger here...