The person hiding in the mirror was Illuso from the Hitman Team. Fugo ends up being dragged into the mirror by Illuso's Stand, Mirrorman. Fugo then summons his own Stand, Purple Smoke. Despite Giorno wanting to find Fugo, Abbacchio decides to go look for the key, since that was their mission. However, once Abbacchio finds the key, he also gets dragged into the mirror world...
Seriously, what the hell are 
you doing, you bastard?!
!بحقِّك، ماذا تفعل بالضبط أيُّها الحقير؟
Was bei der heiligen Mutter
treibst du Wichser da?!
¡¿Qué crees que haces, infeliz?!
¡¿Qué crees que haces, infeliz?!
Qu’est-ce que tu fous,
espèce de taré ?
Ma che cazzo hai fatto? Sei matto?
O que você está fazendo, porra?!
Ты сумасшедший! Зачем её рубить?!