I think it's important to take note, though, that the only (canon) mutant blood color is bright red. Karkat is not a lowblood with a mutation. He should have had green blood. There is no correlation between what their blood color would have been without the mutation and what it is with. It will always be candy red, not bright purple, not bright yellow, candy red. That is the mutation (once again, this is from a canon perspective), bright red blood. Not bright blood. Bright. Red. Blood.

Very good point.
Karkat WOULD be a limeblood. But mutations and shit.

Gosh darned silly mutations.

-Mod F