As a kid collecting comics this was something I never quite understood.
Mantis was thought to be dead for years up until the Crossing I believe.
Which death was the one that made everyone think she was dead dead and not oh I can come back later dead?
Was it the one where she was killed in an explosion by the Elders of the Universe when they were fighting Silver Surfer or was it in the battle the Fantastic Four had with Kang? I can't remember which one was supposed to be her real "death". I seem to remember Silver Surfer grieving for her after the Elders caused death but I remember her coming back from that one and I don't remember anyone remotely caring about her when she died in the Fantastic Four story with Kang.
I seem to remember seeing her alive again after both deaths pre-crossing even though she was always referred to as dead in the comics.
Nah, the only person who thought she was dead was the Silver Surfer, and he's a bad judge of these things. The Avengers learned fairly quickly she was a body hopper.