So you said that davekat is canon red right now. I was wondering if before retcon if they were black or any other quadrants. I knew there was like a whole love triangle thing over terezi, like... i think karkat wanted both red and black with her but it didn't work out. plz tell me if i'm getting any of this wrong.

Karkat had mixed red/black feeling for Terezi, yes. Dave and Terezi were in Red pre-retcon but then she started sneaking around with Gamzee in the black quadrant which made Dave uncomfortable and he broke up with her. Karkat and Dave had no relationship between them pre-retcon.