Mine do the same but I started drilling into their heads they are all they have you are brothers brothers don’t fight each other my youngest starts the fights due to the 4 year old not wanting to play with half the time

What are they fighting about? I would do more things with them that promote cooperation. Find ways that your older son can help your younger one. We have 3 boys and our younger 2 are close in age. We have a zero tolerance policy in our home for physical violence and name calling. We are consistent and clear about our house rules from the very beginning.

It drives me crazy and it’s my youngest who be starting the fight.

That’s all my boys do! It drives me crazy, when mine start I just make them go on different sides of the room.. only works for a min or 2 but hey I’ll take it lol