X-Men: What Happened To Everyone Who Became The Phoenix?

During Amber Hunt's possession by the Phoenix Force the ensuing battle saw both of Rose Autumn's parents caught in the cross-fire and melted into lumps of metal. This was a shock to Rose, as she had no idea her Ma and Pa were robots, and this triggered both her latent abilities and her alien DNA.

Having helped to defeat Amber she absorbed some of the Phoenix power for herself and collapsed, waking up fifty years in the future where all was revealed to her. She was created to stop the Progeny from ever showing up on Earth.

After she achieved this she disappeared back to her own timeline, where she still waits to this day for a sweet comic book reboot.