That's a strange comment. Serri looks like this girl's brother?

A metaphor perhaps?

Perhaps.

But right now it's a history lesson on the Cheysuli.

"I am sorry. I am Niall. And this is my lir Serri." He motions his hand down at the wolf at his feet.

"A lir is something all Cheysuli men get when they come of age. It varies from warrior to warrior, but eventually we all get one. I just happened to be the one to set the record for the longest any warrior has gone before receiving a lir."

He waits, wondering if this strange girl wants to know more about the lir.

You should tell her anyways, lir; she doesn't know of our world.