Marl is vaguely based of Selwyn's original concepts of a shape-shifting monster. Sel was originally a physician of some kind. Marl is a humanoid monster who is half or possibly more- composed of surgical implements and first aid stuff like sutures and bandages. Heavily inspired by the Oogie Boogie from the Nightmare before Christmas movie, his outer skin is merely a cover for all the metal devices and miscellaneous stuff that he's made of. There's meat and organs and liquids there too, but the gauze and steel is messily mingled and travels through everything except the skeleton frame freely. If he breaks a bone, it will "set" itself with the help of whatever tools and parts are in him. Open wounds suture themselves up, it's his natural means of healing and it works faster than a regular human could heal, though the time for a scar to fade or a limb to be fully functional without hardware is only about 1.5 to 2 times faster than the average human. His tolerance for pain is much greater than most living creatures and it is hard to say what hurts him and what is inconvenience. This is mainly due to the fact that under stress, he tends to naturally decay and fall apart. His whole purpose is to be creepy and horrifying, so it's more annoying when he is injured than painful.

He eventually will learn to better control himself to fall apart only when it's advantageous. Overall, he can mange to summon specific items at will, though controlling more than one or two items, or types of items at a time is difficult. In the image, having multiple tendrils of bandaging is not too hard to manage, especially if they are just writhing about. Getting them to wrap or hold things gets harder the more complicated a task is. He can use one or two to write notes, but can't do much more than grab and hold, or tend to his or someone elses wound at a time. He can't treat humans, or perhaps he can learn to eventually. The syringes, bandages and tools he is made of are fear based and would probably infect or damage a human, but will help heal a fellow monster almost as well as he can heal himself. While he could theoretically apply his knowledge to using "dead" tools and items in the human world, it would be very perturbing to work with tools that have to be operated physically, not mentally. Encountering these kinds of items in the human world as lifeless and never having been a part of another being, or not saturated with fear would disturb him immensely. Much like the average person being asked to work with corpses with only vague exposure to death and dead people.

He's a bit aloof and clinical. Much of this relates to him trying to avoid stressful scenarios that will end up in him gushing blood or otherwise having issues with falling to pieces. He's outwardly calm and can deal with other monsters in an emergency type scenario better than a casual social situation. He's probably the sort to drink and smoke heavily to manage stress. Usually quiet and picky, he likes to be in control of his little world and interactions, but isn't too concerned with others as long as they aren't intruding. Defends his own space and will hold his own when he must, but prefers to avoid conflict in the pursuit of knowledge. Prideful about his work and knowledge but will not let this get in the way of becoming better still. If you do not want an honest opinion, don't ask, his bedside manner leaves much to be desired. Fairly skilled at understanding others psychology and needs, but he doesn't often understand them or empathize with others. If you are hard working or good at what you do,you'll have his admiration and respect so long as you are always trying to be better. Technically he's young but came into being rather than being born, so his maturity's about 16-18 emotionally, but physically and mentally he seems to be in his 20-30's. In actual human years he might be anywhere from 5 -16 years of age, but time moves differently in his world and over 4 years can be considered old for some kinds of monsters. Basically, he's around a teenage mentality, but considered a young adult physically. In his world, he's old enough to be an adult, but he still has a ways to go educationally and emotionally!