Twin Feelings

Rin is enjoying the purest ecstasy while all Len gets is to suffer the earnest agony. Yet there is nothing unfair about it, because they're twins. So as a pair of twins they simply have one half experience the ecstasy while the other goes through agony. It doesn't matter which is which any more than which hand is which when you're masturbating with one while choking yourself with the other. Ah, being twins is truly such a miracle!

P.S. And with any luck they might even combine death and conception!