"Black Rainbow" was the first novel I read written by J.J. McCoy, and I enjoyed it immensely. 
 I wouldn't necessarily classify their story as "instalove", but they did have a one night stand that they both couldn't get out of their system, due to their incredible sexual chemistry. They both decided to indulge in the affair for only a week, and then go back to their everyday lives -- no strings attached. 
 Did they have plenty of sex? Yes, of course they did. That was what the week was supposed to be about, but in-between their hot and erotic encounters, they talked and got to know each other a little bit. They both started catching some feelings, which they didn't admit to each other, before they both went their separate ways. Now they're back in each other's lives in the real world, as teacher and student. He tries to chase her away from his class, but she refused to be intimidated by him. The undercurrent of desire is still humming between them, and eventually they both acknowledge that their resistance is futile. 
 I loved these two characters! Levi's an awesome romantic hero. He isn't one of those overly aggressive alpha types, but he doesn't take any crap either. He's perfect for Thea who is a strong and independent woman that's smart and wants to be the best lawyer she can be. Due to the difficulties of her past she has built walls to protect herself, and Levi is patiently and persistently tearing them down brick by brick. 
 The plot is steady-paced and well-written, but where I think McAvoy really excels in her writing is with the witty banter between her hero and heroine. It reminded me a lot of "Moonlighting" or "When Harry Met Sally". I couldn't help but smile at the two of them as they went back and forth with each other. I LOVE great dialogue, and I really think she aced it! (On a side note: you can see additional proof of McAvoy's talent with witty dialogue in her book "That Thing Between Eli and Gwen". I LOVED that one!) 
 If you enjoy books with legal intrigue, (in the vein of "How to Get Away With Murder"), scorching hot love scenes, and a taboo professor/student romance between two likable characters, I would definitely recommend "Black Rainbow"! :)