She came form the future to save the Marvel heroes form the 1950's. She first met them right before they all sacrificed themselves in order to save the planet from the Skrulls. After that, Cassandra traveled back in time deeper and deeper in order to save them. She had met Spider-man on one of her travels tot the past.
She was involved with a cyborg named Gene. Her lover underwent radical genetic alteration for life in deep space and he even assisted Alexander Locke in locating Cassandra's evidence of Skrull treachery.