He is a truly obese man, unable to move without assistance. When overexerting himself or during moments of tension, his metabolism causes him to drastically lose weight, making himself far slimmer.

Gruyere adheres to a philosophy of the "inner beast" that is to say the ambition that drives one's actions. He believes that every person has an inner beast of their own, and that life is about finding that beast and nurture it. For Gruyere that is battle, and he takes immense joy in finding a good opponent to face.

Gruyere Soljest is known as a wise and smart king, being able to control one of the strongest militaries in the west, and also a food connoisseur, gathering chefs from all over the world to make the best food for him.