Unfortunately, all the Guardians except for Rocket and Nebula faded away post-Thanos snap, but with Avengers 4 less than a year away, it’s a good bet that those who disappeared (well, the heroes at least) will have their fates undone.
Once Ego was dead, Mantis was welcomed as the Guardians’ newest members, staying with them until the events of Avengers: Infinity War.
After that, though, it’s unclear what’s in store for Mantis and her space-faring allies, as Guardians of the Galaxy Vol. 3 has been indefinitely delayed in the wake of the James Gunn drama.
Ego had Mantis use her empathic abilities to put him to sleep when necessary, but once Ego tracked down Star-Lord (his son) and the rest of the Guardians of the Galaxy, Mantis knew it was time to leave her master’s side.