The seme sleeps with some uke he met. Then he goes somewhere else and sees the uke again. This uke appears to not have remembered who the seme was but then the seme was like: didnt you just sleep with me, and the uke was like oh right... then he sleeps with him again. Unbeknown to the seme, the two ukes are twins. At first, the ukes slept with him cuz they're into incest and sleeping with him would mean indirectly sleep with one another but later on, they fell for him too. I swore I just read it recently (within the last 2 years) but I just cannot find it anywhere.
Thanks in advance.