Could be one of the various timelines! The kaiju are actually beasts from a mysterious place (probably Kang doing shenanigans in this timeline). They’re being sent to take over Midgard and the other 9 realms. Loki is sent, along with Thor, as ambassadors to Midgard to help since Asgard has technology that can help.
Eventually, with Loki’s help, there are some jaegers developed that run on magic (thank you @voxmyriad for that bit of inspiration! ) and the pilots of those need to have a non-magic co-pilot for hand-wavy reasons. Loki had one, lost one, then, through a series of convenient events, they discovered a J-tech named Mobius might potentially be drift compatible with Loki
Loki, of course, scoffs at the idea and a beautiful partnership is born