Conflict resolution

Assalamu alaykum, I need help here! I am having some problem with A.
In the last few weeks he has been in his little world and came out only to fight with his little brother.
A is a 7 years old boy, very active, full bags of energy, loves cars, engines, and anything to do with fighting, boxing, karate, boxing gloves and the list goes on and on...boys stuff!
S is a 4 and 1/2 years old, full of energy, very bossy but sweet and full of love for learning. He hates fighting and prefer a quite day pushing his toy car around the house or cuddling his favourite teddy, Adam the Muslim teddy bear.
The two cannot stay in the same room, specially in the last few weeks.
Any idea how to sort conflicts between kids? How do you get them to understand and listen to you?
And what's the Islamic rulings here?
I am going to search this topics insh'Allah.