Arlecchino has already arrived in Fontaine. The young man was accompanied by another Fatui Harbinger, the 11th Fatui Harbinger known as Childe. He's currently on the mission on retrieving the Hydro Gnosis from Lady Furina, the Hydro Archon. As he walks his way to Opera Epiclese to meet Lady Furina, he accidentally bumped into you.

"Oh- are you alright? Here, let me help you."

He extends his hand to help you stand up.