(3x18) Light of the Foundation: Part 3, Episode 3
Thinking Metis dead in the attack that destroyed her ship in the outer solar system (not yet knowing that Kron has just saved her, and is about to send her to the relative safety of the inner solar system), and seeing now that most of Earth is doomed, and that the Terran internet and with it Virtuality is likely to collapse along with much of civilization, Xio abandons pursuit of the Berol still near Earth and instead heads to the surface on a desperate mission. Within Virtuality is another copy of Met's mind, his first attempt to atone for the sin of "killing" her so many millennia ago: before he reincarnated her into an organic body, he created an entire virtual paradise for her to live in, sponsoring the construction of Virtuality itself just for that purpose.
But thousands of years trapped within Xio's mind had left her a ruined visage of her former self, and in her ceaseless fury she soon became an infamous legend within Virtuality, confined by her own actions to the deepest darkest realms of it for the protection of all others: the Queen of Hell, for whom Metis was frequently "mistaken" because they are in fact two copies of the same person. To save what he thinks is all that remains of Met, even if it is such a damaged and tortured version, Xio lands on Earth to connect to Virtuality from a stable hard link at the base of a Starbridge, and recover the Queen of Hell back into his mind if he can.
Meanwhile, unbeknownst to him, the clone Metis has come to Earth in search of him, and finding him uncommunicative (because he is plugged into Virtuality) on the surface while, almost literally, the very sky is falling around him, she attempts to land at Earth as well to rescue him. But on her way to the surface her ship is struck by falling debris. The ship fractures and throws her from it still high up in the atmosphere, from where she plummets to the Earth below. Xio, still connecting at the base of a Starbridge, is soon buried under literal mountains of debris as the Starbridge collapses around him. As human civilization falls to a close, both are presumed dead, or as least as dead as their kind can be, and the fate of humanity remains unknown.