1) Playable Characters central or central adjacent to the main story with (reason) for relevance
>Skirk (our abyss liaison with highest connections)
>Cheld (fatui harbinger)
>Arlecchino (fatui harbinger)
>Venti (Istaroth connection)

2)Future playable units with probable relevance
>all future harbingers
>Tsaritsa
>Alice and co.
>Varka

3)Playable units that might have relevance
>other archons
>neuvillette
>durin
>albedo
>wanderer
>klee (solely because of her mom, no other reason)

4)Has no further use in the story
>literally everyone else

Unless you rolled for someone in categories 1-3, that character will be discarded and forgotten. You might see them in a throwaway event sometimes. But they might as well be literal who's from now on. Keep that in mind when rolling.