When the thing that isn't Melanie in Melanie's body walks through the entrance to their hide out Jared is seized by a strange mixture of feelings that he can't control. There is the urge to hug her, pull her close, inspect her for injuries, but she won't have any. Not since the Souls got a hold of her.
There is the urge to choke her and watch the silver fade out of her eyes until Melanie is Melanie again, even if she is dead. But he can't hurt Melanie, even if it isn't Melanie in there anymore. No matter what he tries to tell himself, he can't do it.
He just doesn't know what he can do.