Ever since he killed Twilight and Luna, Celestia was forced to come out of retirement and rule Equestria alone. In an attempt to return to Equestria, he and Chrysalis kidnap Celestia and burn her at the stake, then Chrysalis will disguise herself as Celestia to cover this up and she will become the new ruler of Equestria and nopony will ever know. As for the OC, he’ll pretend to be redeemed so that he can go back to his old job before he met Twilight: a music critic for his own independent magazine, while creating his own music to earn some extra bits.
 
Of course, he is prepared in case Chrysalis goes rogue and tries to kill him. He also seems to care about Trixie for some reason and will murder his own Queen if he has to.