I did this "only" 3 weeks and finished a little before I decided to join DeviantART.

There are two demon brothers, Ryfer'ein and Gryma'khon. And the little black creature is called a haarisu. Gryma is the sitting one

Story in picture:
Gryma is depressed and Ryfer tries to cheer up his older brother. He had summoned a haarisu and dressed it up and told it to give flower to Gryma and now he is showing it to him.

Info:
I got the idea for haarisu from the shadow heartless in Kingdom Hearts® (sorry) with exceptation haarisus have tail and wings (which are under the shirt in this piccie). Haarisus are "shadows of the summoner", they're kind of part of the demon: demon uses a little magic to summon/make haarisu, haarisu does whatever told. Or something.
Other thing worth noting is that demon's albino is different from our albino. Albinos aren't exactly popular amongst demons in my world, despised to be honest, because they're different in a few ways.