Well, Zane will definitely know who Rose is (he has a canon line in his show about stealing TARDIS blueprints when hacking a supercomputer, so he was a fan long before the universe traveling) and he knew a Rose in War. Same with Rebekah; he'd known her in War, and one of his best friends in NOLA is dating her brother Klaus (Cami O'Connell) and has a kid with him, who he considers like his little sister. So he's familiar with Mikaelson family history thanks to that. He also knows a Katie in NOLA but she looks different, but he's used to that. And Teddy will be familiar since he knew HP characters in both places. Once he gets over the "doom and gloom" mood, he'll definitely be down for being sociable with all of them.