If my little brothers are being bullied by kids half my age how do i deal with that? (my brothers are 8)(and im 16 but i dont want to hurt the kids but i want to get a message through)

Talk to the kids and make sure they know to stop

You could probably tell them would they want to be treated the same way they are treating your brother. That normally helps because when you act towards someone its most likely going to turn around and hit you.