they have never, will never, and could never be good for each other. they are similar in ways and opposite in others where all they do is tug at each others worse impulses no matter what terms theyre on. vriska could never stop being jealous of terezi, as terezi stands as a vision of effortless skill, heroism, heritage honoring, and consistent narrative importance that is everything vriska strives for in a bullet point list. that jealousy only serves to fuel vriskas self importance. in the first half of homestuck a large chunk of vriskas character is defined by her being a “lesser terezi". anything that reminds vriska of herself draws her in. but where terezi is only an extension of vriskas self vriska will never care for her as much as the real thing.

in terezis black and white morality vriska becomes an either a cartoon villain (murderstuck), or a paragon she should unquestioning listen to (flarp, retcon). terezi feels as though caring about vriska is all or nothing: she can care about vriska and prioritize vriska OR about and prioritize everyone else she knows. symbolically her choice to kill vriska is represented by the image of her and karkat together: the decision she makes is to literally choose to put her relationship with karkat first. her choice to cause the retcon / save vriska only happens when karkat again becomes something she needs to solve for. terezi would never naturally put vriska first.