Hunter/Slayer power puts him on par with the Originals, and then some?
Katherine comes to town and gets a nasty idea upon spotting Jeremy and her doppelganger. Comes in and compels (Think she does) Jeremy to fuck her, telling him it's a dream come true, then Elena walks in and is shocked and confused.
Elena walks in, which slows his humping before he picks it up again, much to both their surprise, says Best dream ever. Amused Katherine helps with a bit of compulsion, finding it exciting.
Compels her to join, and is fine with a 69 position with her doppelganger, for there isn't anyone she loves more than herself, while Jeremy has his way with them. Then Jenna is caught and forced to join, and Jeremy has the best time of his life, and even Katherine isn't disappointed with how things turned out, deciding to stay, falling for herself/Elena, and her family, adopting them as her own.
Maybe pretends to be Elena's long-lost twin from there on???
Nadia joins later, happy to be reunited with her mother more intimately than she could possibly ever have imagined.
Bonnie, of course, gets fucked into submission during a sleepover, with Katherine urging Jeremy on, so as to bind the witch to them for what's to come, who was happy to join her best friend Elena.
???Maybe later starts to collect doppelgangers, unwilling to let them be with anyone else. A harem of dopplegangers in the future???