<human>: i know a little demonology but i cant find a certain "type" of demon i need for my story. The plot of it is that one day a girl is attacked my a evil guy but the guy is killed by a demon and the demon is the girls guardian/crush.the two go on through the story killing evil people while the girl tries to "save" the demon. i am trying to find a demon that can be evil yet human-like emotions or "loving", it can be from any religion or mythology i am just looking for something that can be my main char that falls under the title of "demon". I remember reading about a demon that is made of shadows (not a wrath) and wants to help humanity but we are afraid of them and it makes them depressed, they are the demons of sadness or darkness something like that but while googling all i can find is high demons/ old gods and i am more looking for a "Type of demon" rather then a specific name.

Can you condense the text into a few key points?
<bot>: writing story,need type of demon for main char, must be about to kill but not that evil, kinda misunderstood demon type or something close to it.