Rin Okumura's little puppy - Blue Exorcist Rin x OC

In this story, Rin falls in love with another half-demon half-human girl. But instead of having a tail like Rin's she has a tail that is more like a wolf, she also has a pair of wolf ears as well as the pointy ears. She acts like a puppy most of the time that she is not working. She also has the senses of an adult wolf, like super hearing, smell, eyesight even though she isn't blind, she can see a bit better than humans. Rin finds her wolf features cute and adorable. Her wolf features let her shift into a wolf of any size, but she generally chooses to shift into a wolf pup, showing her submissive side. Does she feel the same way as Rin Okumura? Or does she reject him?
Things might go a bit quick in this story, I generally put the two main love interests together within the first chapter.