Belle
I would like to remain close by, in case she loses control. But I believe building connections to people is the best way to control her powers.
She is terrified of what they can do, and has sought all these years to suppress them, rather than working with them. Henry says in her world she finally gained control through love, which is after all the most powerful magic of all.
I don't know if I can fix it. I shall try, but she needs to open her heart. And that, as we all know, is incredibly difficult.