The power of anxiety
Karkat Vantas can not stop fucking thinking. It seems that every moment of every night his brain is running at full capacity, constantly calculating, contemplating, considering. One might consider such a mind to have trouble sleeping, and indeed he is said to have spent his entire session in a state of wakefulness.
Karkat does, of course, have a lot to think about. His blood colour makes it all but impossible for him to survive adulthood under the violent Alternian regime, and this fuels his paranoia with keeping himself clean and unblemished, his fixation with emulating the proper behavior of an upright Alternian soldier, his love of the Thresh Prince, a story about a member of the (relative) underclass breaking into highblood territory and proving himself worthy.
But these habits make themselves known in other places. Notably, Karkat is one of the teenaged protagonists possessed of the unusual ability to keep his room clean, which he does with such extraordinary proficiency that it can perhaps even be called spartan. He keeps track of his team, too, and in the middle of the endless, uncontrollable noise he constantly spews at himself and others, there are orders, directions, and general coordination. Karkat, generally speaking, has a decent grasp of what the things are that need doing, and roughly who needs to do them, and he’s not afraid to tell them so.
But his powers are not merely situated in the present. When left alone, Karkat mulls over things, turns them again and again in his head, and occasionally hits on surprising revelations, like his understanding of Jack Noir as a metaphorical cancerous tumour in the universe frog he and his team created, aimed squarely at the frog itself (or his considerations on the nature of free will in a universe with an Alpha timeline).
It is Karkat who finally breaks the code of silence regarding the pre-retcon meteor’s plethora of growing issues. It is Karkat who figures out that chairs are handy to have, so you might as well keep one on your person at all times. It is Karkat who patiently tries to work countless others through their problems, with his mind always buzzing, spinning, and turning with the countless little details of the world, all the myriad little sticky details of life, all the endless ways things can go wrong.
And yeah, it’s unhealthy. Homestuck is full of people pushing through difficult situations by applying their mental problems and maladaptive coping methods best they can.
smells like some ADHD is mixed in there, too
Oh yeah shit I forgot anxiety is a technical mental health term and not just a colloquial description of a common emotional state. I have no real position Karkat’s nature vis-a-vis the DSMV. Medical anxiety problems, ADHD, both sound somewhat plausible from my perspective I suppose, but I also know I’m bad at identifying mental illnesses so I’m not going to say anything really.