Isaac Lutz

Isaac is a demon who found himself taking up a job as a barista in a cafe chain.  He comes across as disinterested, sarcastic, and bored to most he meets while working.  Not long after he began working there, however, a rumor began to surface: If you order the brimstone special from him, you'll get the best cup of coffee you've ever had in your life. For a price.

It was almost surprising to him just how many people were willing to sell their souls for good coffee.

- Isaac is not his true name. His true name is kept secret out of fear someone would have power over him if they found out.

- Really good with names and faces. If he's served you before, he'll remember the name you gave him.

- That said, he'll probably misspell your name on purpose on your cup. It amuses him.

- Has sharp teeth. Refuses to change these.

- His sclera are sometimes a dark green. Usually only when he's in a bad mood.

- Is awful with pop culture. Wouldn't recognize a celebrity if they were right in front of him unless he's previously met them.

- Feels negative emotions more strongly than positive ones, but is capable of having feelings for someone. These would likely get overwhelmed by jealousy or self-doubt.

- Has trouble maintaining his human guise when angry. Details will often seem 'off' when he's particularly upset. He is pretty difficult to anger, however.

- Strongly dislikes children.

- His tail is not visible when working, and has a mind of its own. Isaac treats it more like a pet than a part of him.

True form is significantly less humanoid, basically a big plant-y hellhound.

This character started as a joke character of sorts, with the whole trope of people drawing nonhuman male characters as handsome blondes if drawn as humans. He kind of grew on me with time. 

Accepted headcanons from other people:

Most of the customers come in to try and confuse him with long orders, but he always remembers each one and recites them back to people word-for-word without even blinking. - by PicklePantry