See this is where I am getting caught up as well. Honestly, I would accept Harper's sister and/or dad. That assumes her sister is the nurse with the eyes from waaay back. People with parlor powers finding a way to take real power seems like a good motive to me. But even before that, I just want to know if the blonde on the subway, in the jewelry store, and literal lady of our dreams can shapeshift into the cat so that the villains can get intel on us. Beyond that, I am struggling to find a motive beyond the obvious for kidnapping the top hero in the city and this has me grasping at so many straws. I am still holding onto the idea that grandpa will help us fight someone later and give us a huge power boost during that time. See, straws.