Armin hasn't really interacted with Gabi much since arriving - doesn't know her all that well, bit young for company, not on the world's best terms with Reiner, etc. - but in his young state, he doesn't seem to recognize her at all. There's a shocked (if not slightly horrified) expression on his face as he watches her swing the net around, screaming. It had been such a peaceful night...

"I-is that really necessary?!"