ROTTMNT: Leonardo was successful in trapping Krang prime in the prison dimension. His brothers not giving up on him help Mikey open a portal. Though In the process of brining Leo out the portal glitches brining Leonardo to the bad future. where him and his brothers a 8 years into the Krang invasion. (None of the brothers have died yet) Leonardo knowing the future of this time decides to help defeat these Krang, while also looking for a way to his own time line and maybe trying to prevent both timelines from collapsing in the process.