Gressil is notably unclean and messy. He tends to wear a pair of dark green coveralls and no shoes. His hair was a greasy, curly mess of black and he has dark rings under his yellow eyes. His center, top teeth are missing and the ones closest to them have been filed into fangs.
Gressil is very eccentric and loud. Many are, if not putoff by his appearance, repulsed by his behavior or odor. He, himself, cares not for what others think or say of him. He often reacts in digust or spite when soap or cleanliness is brought up, possibly hinting that his Demonic representation is of filth or stench.
He has a playful, almost childish personality, often cracking jokes and cackling to himself. He often makes up nicknames for people based on his opinion of them, calling Azazel "Boss", Beelzebub "Mr. Suit", Forcas "grumps", Sadow "Squirt", and Naamah "Tits". Despite this clear absence of respect for others, he does know when to fall in line when signaled, such as when he abruptly stops joking in the middle of an Apostle meeting when Azazel stares at him.
He seems to have a bit of a sweet tooth, constantly delighting in nearby confections and even taking from Beelzebub.