(Underswap)
Papyrus accidentally sees the Swapfell bros going at it, with SF!Sans sweetly, gently, destroying his brother's ☆ss. Pap's been the top in his and Sans's relationship so far, thought that was just how it was supposed to be, but that absolutely blissed out look on SF!Pap's face as he begs for more has him curious, longing, envious.
The next time he and Sans are intimate, he can't stay aro☆sed because he's realized just how not-into topping he is. Sans fusses over him, asking him what's wrong, and it takes some prying, but Papyrus admits he really just wants his older brother to take care of him. Sans is super supportive, praises him for being honest, and lays him down. But all Papyrus has ever summoned before has been a d☆ck, so that's all he's got to work with right now on short notice. Sans still praises him, climbing on top and riding him nice and slow. Promises that they'll work on this, that the next time they make love, he'll take Papyrus's v☆rginity all over again. "* WOULD YOU LIKE THAT? BEING WRAPPED SO SNUGLY AROUND ME. I'LL BE SO GENTLE, PAPY, I'LL LOVE YOU RIGHT--" and Pap is gone, already coming, crying at that fantasy, that promise.













