Belzebuth from I'm the Villainess, So I'm Taming the Final Boss (ITV SITTFB) is a fiercely loyal, rough, and easily angered demon lord's subordinate who hides softer emotions, becoming loyal and learning manners from Lady Aileen, despite his initial boorishness and hot temper, often acting as a bodyguard and showing surprising development.

Key Personality Traits:

Loyal: Extremely devoted to his Demon Lord, Claude, and fiercely protective.

Hot-headed: Quick to anger and disrespect, lacking refinement due to his upbringing.

Hidden Depths: Beneath his rough exterior, he possesses softer emotions and a capacity for loyalty and appreciation, especially towards Aileen.

Mannerly (Eventually): Learns etiquette and develops a fondness for Lady Aileen after she teaches him.

In essence, he's the gruff but ultimately good-hearted (or at least trainable) demon who's fiercely loyal and grows significantly as a character through his interactions with Aileen.