Grillby works alongside Muffet at their resteraunt, as he is the head chef and manages the resteraunt's main buisness. He also doubles as a field agent for Sans, working with him and leaving Muffet to keep an eye on the shop when he's busy. Grillby has a calm demeanor, often sometimes falling silent altogether but speaks when needed to. He is also kindhearted and sometimes when he isnt busy, hes seen helping other small businesses or elderly take care of things they cant handle themselves, like volunteering for work or running errands.  It's not made obvious, but Grillby is very close to Sans, the two being childhood friends and Grillby sometimes  teasing him with some light wholesome flirting once in a while just to get him riled up XD. Grillby is pretty smart, willing to work alongside Sans in the lab to help him with stuff Sans cannot do himself. 

Grillby chooses not to form his soul into a weapon, so its unsure what his weapon of choice is. He prefers his fire magic altogether, able to assist by lighting dark rooms, scorching his opponents and melding things together with the heat of his flames. He might not be much for an offensive, but he's got the defense to pull through most of his battles stable

[Grillby should be soft spoken with a soothing and calm voice. You can give him an accent if you want, but he can work with and without one. Have some fun with it!  :D]