I read this within the last 5 years, so somewhere in the 2012-2017 timeframe. I don't remember exactly why I lost track of it... western art style, involves a young boy who has a succubus emerge from under his bed. He winds up getting her to try cookies, and she finds she enjoys them a great deal. As it turns out, she's immature herself, just starting out. I want to say that it's a standard monster under the bed scenario where her race gets energy from scaring kids.
Anyone, they start falling for each other in an awkward sort of young love way, complicated by that she can't let her superiors know she's revealed who and what she is to a human. I remember there being a capital-letter Council referred to. The other thing I remember about it (which may account for me deciding to stop checking in on it) was that there was occasional female nudity due to the demons not really having any real attachment to clothes.
I think she was blue or purple, had either horns or long ears, and had wings of some sort. They at one point sneak out for cookies from the refrigerator in the middle of the night and he has to hide her from his parents, that sort of sitcom hijinx.
And... found it in the process of doing a search for webcomic Monster Under The Bed due to me mentioning as much above.