The world is full of people, i don't know why people need to put one point of view above the others! i really don't like the concept of protagonism, in my comic i always think as "who i want to put in the focus right now" and "how much this character is hiding" because if reader see his inside toughts the surprise will be gone.
i'll comment on your concepts, here's my first impressions:
the first two contrast a lot, i love the synergy between their hights and colours, and hairs and expressions, ways of dressing, they are so different it seems like they are made for eachother. and kink is awesome
the trio have a different feeling, the yellow eyes push a lot of my attention, i like this character personality. the other two have that numb traumatized or hypnotized vibe to them. i love the clothes, very nice details!!
Lucifer is sexy. i wanna read that. would love to wear a lot of the clothes you illustrated, you are really sharp on the fashion, wow! your devils as a whole have that queer happy mean lets have some fun vibe!