Insane theories regarding the fanfic Harbinger.
Cerberus is behind Fettel's escapeEither intentionally, in which case they may be attempting to harness his ability to control Replica or to find Alma, or unintentionally, because, well, Cerberus.
Cerberus is an off-shoot of ATCTIM has some significant knowledge of Alma, and is trying to find her. He's also hiding from her, which means she;ll do some not-nice things to him if he wasn't hiding on his shielded space station. Maybe TIM was on the Origin team that was behind a lot of the screwed-up stuff that happened to Alma, and then broke off to form Cerberus.