BG3 Character Swap

Character Exchange Program: One BG3 character (playable or non-playable) is sent to a completely different game, and a character from that game is sent to BG3.

They both fill whatever role their replacement left behind. (be it boss, party member, etc)

(Whether it's treated as an Isekai situation or whether they're rewritten to a new setting is up to you)

What swap would you most want to see both sides of?