Every time people lament changes to the lore that amount to "not every member of species X is irredeemably evil" and claim the game is removing villains from it, I think how villains of so-caleld evil species fall into two cathegories: a) bland and boring and b)have something else, unrelated to their species going on for them, that makes them interesting.
Understandable - I prefer lovecraftian and fey creatures for alien thought processes, and use devils more as a foil/mirror to the lawful god of cities, merchants, and wealth, whomst I hate and will take any opportunity to drag.
I see Fey not as alien, but as capricious. They do what they please, when they please, damn the consequences.
They might commit arson against a local noble and then give that noble’s kid a super fancy cake; and not have a reason for either beyond “lol, lmao”
Always interpreted planar creatures as having an alien thought process in general. That is a good use of devils ngl, for related playing pallies/clerics with 'my higher power is the people' is quite fun.