What can i do with my 5 year old brother?!?!?

there are lots of things you can do indoors on a rainy day. I play hide and seek with my boys, or we will build towers out of blocks then pretend to be big monsters and knock down the buildings. Cleaning up afterwards you can have a contest to see who gets all of their blocks put away first and there could be a good reward in it for him afterwards, like maybe apple sauce and graham crackers or a posicle. There are so many things that you can do that are fun....maybe a game of charades? I don't know your forte but there are lots of educational things you can do that are fun. And you could always ask him what he wants to do too.