I'm going to knock out the fool who was giving my brother drugs
Why would you knock someone out for that?
He gave him ecstasy and then my brother overdosed
Even if you know who was responsible for it you shouldn't go beating them up. You should look into reporting him to the police instead of trying to take it into your own hands.
Yeah, I'm going to do that.
I'm glad you're not going to resort to violence! I know you are mad, but hurting someone else will make you responsible too and your brother might feel even worse getting you involved.