For caitvi maybe it could be Vi and Jenny, and Caitlyn with the night nurse.
VI and Jenny I do not have much reason besides tattoos and VI's pit fighter look.
Caitlyn and the night nurse cause with Cait being an inforcer and the night nurse keeping dead children in check they both have jobs that are there to keep order in some way.
With Mel and Monty switching that does leave Ambessa and Ester as an option.
The other characters I am not sure with are tragic mick, the cat king and David.
Arcane/DBDA swap au?
Viktor swaps with Edwin, Jayce and Charles, Crystal and Ekko and then Niko and jinx
Viktor and Edwin I don't have much reason for tbh
Jayce and Charles cause I think Charles would think the hammer is very cool
Ekko and Crystal because magic and also because I think they'd look cool in each other's outfits and I think they'd get along
Jinx and Niko really only for timebomb's sake but also cause I think Kingham and Litty as Silco and Sevika would be fucking hilarious
Mel and Monty perhaps because of the relationship with Ambessa and the relationship with Esther remind me of each other
I have zero clue who would be caitvi
Everytime I watch episode 5 Dead Boy Detectives I get hopeful for Jenny's date then I remember that it didn't and I get sad again. Why can't she get a nice date.