Sol Returns

A mysterious new figure comes to New Mewni. He reveals himself as a human named Sol Veinte, the son of a supernatural government agent who disappeared from Earth several years before the arrival of Star, but turns up hostile and demanding to see two girls named 'Small White and Little Yellow'. Star and Marco find him and get beaten up by his superior fighting skills and surprising ability to use Mewnian magic. Calling the Lodgers and Trista Hylander, they discover out of nowhere upon another confrontation that the ones Sol was looking for was Trista's friends Rapae and Lisa, who were friends with him and were looking for him for years. Reunited at last and told to his surprise what happened to Earth and how it's merged with Mewni, he is happy that his world is now merged with his obsession with magic and fantasy, as he explains his story on how he was an outcast for trying to prove magic really exists and how he used and lashed out at Rapae and Lisa for getting him in so much trouble that he nearly doomed his home to a singularity of a pocket dimension of pure magic, which he sacrificed himself to shut after admitting he was in love with the two twins. He then explains that he was trapped in a sci-fi fantasy dimension where everything was out to get him, including a new arrival: an ancient Mewman witch named Lady Salem, his arch nemesis and the descendant of the original Lady Salem who gave birth to many sub-Mewmans during the times of the Salem witch trials, and wanted revenge on humans for their false accusations but was banished to another dimension by a Mewman princess. She wanted to kill Sol for being a human and ended up following him back home. Now she's back for revenge and the heroes need to stop her.