Harley takes a moment to catch her breath after Chara tosses the smoke bomb and dashes towards the stairs. Being caught in a smoke bomb didn't really disorient Harley (Joker had used his fair share over the years after all).

She stares at the fire-engulfed stairs for a moment. Her thoughts momentarily distracted by wishing Diablo was still alive -- and here.

But Harley snaps back to reality. That loud booming noise might mean someone is in trouble. And she should find out where it happened -- even if it means taking a risk to run through the flames that cover the staircase.