Maybe Kelly will be some sort of healing for Nick. He'll help her out by looking into her case and maybe exonerating her. Nick was supposed to be a parallel for Kelly in Grave Danger. Both were innocents who got caught up in something beyond their control. They were both trapped somewhere that was killing them (emotionally in Kelly's case and physically in Nick's case), and the people that loved them were powerless to get them out. All they could do was watch. I could see Nick's ability to heal/recover directly related to Kelly's ability to heal/recover. They wouldn't have to get together or even be friends really.
As for Lady Heather, well, she doesn't do anything for me.