I just saw a recent post that had all the trolls we know of from hiveswap and homestuck. Karkats bloodline was not red and put in between nepetas and kanayas I think. I saved it if you wanna see. But I don't remember why it's like that. Do you??
Well the Cancer symbol goes between Gemini and Leo in the horoscope cycle which is why it’s always been theorized that Karkat’s blood would have been Lime Green (the color between Gold and Olive) had it not been for his mutation making it Candy Red.