so assuming trolls and lusi are the same species, and lusi are diploid and trolls are haploid, (or some similar system of ploidy doesnt have to be haplodiploid necessarily) . karkat could be a mutant “lusus” in that hes diploid but hes homozygous for the lusus-determining allele (like complementary sex determination in insects) meaning he develops as a troll. and the red blood could just be whatever you call those alleles that stick around cuz theyre positioned close to the allele thats selected f
*hits my astral bong* you know what nevermind this is fucking weird