Liam is sweet, friendly but when he gets mad he stand his ground to fight. Kenzo a bit bratty and very strong. When they fight over a toy it is as scary as hell. Liam will sometimes get a hard toy, or anything he can grab, to hit orr throw to Kenzo, while Kenzo can just slap, pinch, kick Liam to get even or show his displeasure.
It is a rough situation where sometimes it is hard to separate them and you fear for both of them that someone ( or both) will end up very hurt.
I tried to promote that hitting is bad, I even made a song about it to push it across but all for naught.
But I guess most siblings are like this but in the end when they start adulthood and mature they will become good friends and see the value of each other..