I've had a few new ideas for my story.

It has bugged me for a long time, that Raina and Kaylee are sisters (twins, even) and they have the same job. It didn't seem like a thing they'd do.
Raina seems born to be a police agent. I can't imagine her, doing anything else.
Kaylee seems like the type to be able to do almost anything, but I like the idea of her, being with the police, the most. I like the contrast between how she comes across versus her, being actually very skilled and having a very responsible job. 

Today I solved the problem; she can be like Arthur Weasley. It seems perfect for her. Being a people-person was always a part of her personality; she'd love dealing with both supernaturals and non-supernaturals. And she'd be good at it. 

Another issue I had was with Marielle; she seemed flat, compared to the other characters in the story. Finally I decided to tweak her personality, the main difference being that she's a bit spoiled and egocentric, and that she's not empathic (but thinks she is....). When I told my husband, he said that I already write her that way. Which is true; in the story, she has no clue Raina has a crush on her.

When I created her, I wanted her to be empathic, because Raina has mental health issues. I felt that she'd need someone who could understand. But Raina being the way she is, I don't think that is necessary. She needs someone kind, who has good intentions; sure. She doesn't need someone empathic. She can deal with Marielle, missing clues and misunderstanding her. I think it will make their relationship more interesting.