Grim appears to be a man, human in design, but with ashen skin and hair that varies from black, to silver, to white. He is a bit shorter than the average male, and looks young, almost feminine. His eyes seem normal unless he gets a strong emotion or violent rage, in which case his eyes glow, and the sclera tends to get bloodshot. His mouth is cut into a glasgow smile and healed open, which paired with his pale appearance gives the title.
Grim seems to have the tendency to heal over a long period of time from even fatal wounds. It takes him a day to a year to regain consciousness (year test was from mashing his body into pulp), and most often when he does his body still needs to heal a bit afterwords, making it easy to constantly restrain him. He also seems to move quickly and silently, generating no sound if he wishes. He has been observed to teleport short distances in sight, and seems to have heightened awareness including the ability to see in darkness.
Grim acts childish and manic at most times, making interactions with him difficult and dangerous. He is violent, and not above biting chunks out of staff, and has even been noted to ingest human flesh. Sedation is possible, however, but can leave him either too lost to reality or too grounded in reality to be of use. When done right, he is dazed enough that what caused his madness is not too clear to him to make interactions pointless, but not so dazed that he is incoherent and drugged. He has, through improper sedation, become addicted to various substances which, although cannot cause lasting harm, interferes with observation and research. His speech seems to match a Brooklyn accent, and he doesn't act too much older than he appears, despite that his ability to age is in question.
S.E.R. will do its best to try and offer an attached image once Grim ceases being shy! What a silly young adult this guy is. We would like to encourage socialization and encounters with this obscure youth, to make sure he gets the interaction any young man needs for proper mental health, and to expand our records!