About halfway up the stairs, a short, auburn-haired boy was rising to his feet, having clearly just fallen. Because he was looking back up the stairs in confusion at the time, it was a good few moments before he noticed the newcomer. 

"Oh! There are other people here? I thought I was the only one exploring." 

The boy gave a cheerful grin as he bounced the rest of the way down the stairs, seeming to either be completely unaware of the weapon held by the girl or perhaps just not caring about it. "When did you get here? Did anyone else come? Where have you gone to already?"