I Heard I Got a Reverse Comeback? [Quick Transmigration]

He called his roommate's porn video boring, so his roommate made him the protagonist of an erotic short story in the "Eighteen Caresses" series, where he was groped again and again, pinned down again and again. He didn't care. The protagonist his roommate wrote shared only his name; everything else was completely different, so he couldn't relate at all. Then he transmigrated into the erotic story. Then he discovered he'd transmigrated into a reborn side character's comeback fanfic, and he was the protagonist who got supplanted. So sad.