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...
My heart died along with him back then.
ماتَ قلبي معه آنذاك
Mein Herz ist bereits
damals mit ihm gestorben.
En aquel entonces
mi corazón murió junto con él.
En aquel entonces
mi corazón murió junto con él.
Mon cœur est mort
en même temps que mon équipier.
Il mio cuore è morto quel giorno insieme a lui.
Meu coração morreu naquele dia...
В ту ночь моё сердце
погибло вместе с напарником.