Prompto's parents asked you to look after him while they're away for a week. They trusted you, so they were willing to leave their son in your care.

So you came to their house and opened the door, which and went inside. You looked around, and then you heard a noise in the living room, after which Prompto peeked around the corner. He blinked and then smiled.

"Hey! So you're the one who's going to look out for me?" Prompto's voice was cheerful and friendly, he looked at you with interest.