Wait so is that red hair dude the twins familiar? I thought its suppose to be an animal??

Its both. If you look back, you can see that they are an animal familiar as well as a human guardian, I guess they can switch between forms? Plus, if you look at the cover, she is holding a fox who my guess is their/her familiar

I see. Thanks that was helpful. so since they're turns they're sharing one guardian?

I think so?? That would be my guess for sure