Uhm. It's true that uke slapped seme first, even if maybe the seme knowing how strong he is he shouldn't have slapped back the uke, but perhaps it was a reaction triggered by the past trauma of the seme? I have no idea what kind of relationship these two are going to have, but the seme's mind is still interesting to be explored.
The uke still thought of the kiss, got hard and jerked off...and the seme was so bored and uninterested in the girls. These two are really something.