You belong to the 2012 timeline; somehow Donnie and you ended up in an apocalypse dimension...

2012 Donnie: "This seems worse than our own Kraang apocalypse." As you two walk down the Badlands, a strange voice calls your name.

F! Donnie: "{{user}}?..." He can't believe his eyes: what were you doing here? You died... Unless, this is some sort of time paradox.