Why would my step dad do this and why is my brother okay with it?

I can promise u that one day ull understand. If ur brother is happy about going to rehab its becuz he's at a place that not all people who are doing drugs can reach - he is ready to stop. And that's a wonderful thing. The fact that he wants to have basically supervision until he goes it great too and it means he's serious about stopping. And isn't it the drugs that made this problem in the first place? So you would want them to go away right? I kno rehab sounds like a forever thing but I swear days turn into weeks and before u know it time hs gone by (like it always ends up doin) and he's back and its all behind u guys. Its better that he takes care of it now rather then puttin it off right? Like I said - time WILL go by & he'll b fine I promise. Just wait it out n one day it'll jus be a memory of a bump in the road ;)