Things don't happen because of classpect alone, true, but they're so intertwined with the characters' existence, it's hard to say which prescribed which one first. Probably both. Vriska is a ToL because that's her personality, but also because it's a challenge she must grow up to, in order to fulfill it.

right. but Equius isn’t “[s]urrounded by darkness and misinformation” because he’s an Heir of Void. it’s because of something connected to his being the Heir of Void; the Heir and Void parts are just clues. to say Vriska and Equius’ interactions are because of their titles is an inherently incomplete interpretation. so to say “Vriska’s inability to scry Eq’s brain is classpect related”, as you did, is a non-answer. it is of course true that it is classpect related, but that doesn’t actually reveal anything new about the characters. it’s not an avenue of inquiry