A simple man who would be content with merely doing his part, if it weren't for his strong sense of justice. The urge to correct any perceived wrong is too strong to ignore. But what is right and what is wrong? He wasn't raised to know the nuances of morality and has nothing but his gut feeling to go by. He is prone to violence, perhaps in excess, against those who he deems to be wicked. Forgiveness is a trait of the virtuous and is wasted on the evil, and he thinks himself to be neither. The left hand of the law, of god, or whatever else you believe in - he does what he believes anyone truly good shouldn't do, but is nonetheless necessary.
Under more cordial circumstances, Grigori isn't exactly socially adept, but it can't be said that he doesn't appreciate company. Though it would be a mistake to call him one, he can seem to be a gentle giant, calm and somewhat reserved, or even shy in case of attraction. However, in the end he's driven by impulses, not rational thought. Feelings of camaraderie, fits of passion.. once sparked, they can be as difficult for him to ignore as the call for righteous violence.
He has a habit of chewing mint leaves incessantly.