Rose was just lying there looking asleep with some blood on her. he kissed her to save her. she is his friend and he wanted to save her.
when Jonn appears in the volcano he has no fucking idea of what is going on. he has no way of knowing Jake is trying to bring Dirk back to life. he probably doesn’t even know who they are. the only thing he sees is a guy kissing a bloody severed head.
have you ever seen a real severed head in your fucking life? because that is fucking horrible and disgusting as fuck. now add a person snogging the fuck out of it. not even just. pressing their lips against the head’s lips.
sNOGGING. THE FUCK. OUT. OF IT.