Im confused on the first story, y did the older brother do that?

So the older brother rape his little brother(but he is the uke tho) and the little brother forgot about that incident. And now, after his older brother left the house he is close with this guy, who is his actually his bro co-worker. So when this guy did those lewd things, that little bro remember bit by a bit about his past. Like that

The big bro is the uke??

http://www.mangago.zone/read-manga/d_j_vu_monchi_kaori/mh/c001/43/

Yeah, read this part carefully

So, the lil bro is the uke now?

Yes

Basically the kid changes hands from one molester to another.
He switches from being raped by his brother to being raped by his brother's friend.
But I guess since he at least picked the friend, that's supposed to make it marginally less disgusting.
Still just kiddie porn to me though.