Grace becomes very sweaty, especially at her palms and underarms. She also gets the shakes real bad. When she was younger, she would freeze when frightened or panicked, but now she fights like hell; like a cornered animal with nothing to lose, which makes her dangerous in a fight, because with a mindset like that, she has no regard with the damage she does to herself, meaning anything goes when she's trying to hurt the other person or defend herself.
Grace's alter, the Boogeyman, is much like her, but twice as brutal. To some degree, humans naturally have some restraint to stop you from hurting yourself with your own strength — it's why your brain won't let you bite through your own tongue, for example. But Boogeyman has none of that. When he fronts, he's vicious. Panic for him brings out something twice as horrible as anger because, like Grace, he will fight like hell when he panics. Grace has woken up with cracked teeth, broken bones and other kinds of (sometimes irreversible) damage when Boogeyman has fronted.