Expanding on what rustyfish wrote: a lot of wired stuff happens in those games and Ahti never acknowledges any of it. He is the janitor and he is mopping the floor. He will ask you to fetch something mundane like a tool from the basement which by pure coincidence is the exact place and time you need to be to save the world. He appears in places he should never have been able to get to. You had to fight through many enemies to get there, Ahti is just there.

He is the janitor of the universe, making sure things are how they should be. And then he goes to sing songs at the community center.