So I beat off all the mercenaries in Black Briar lodge and rode away to safety on Frost with his lineage papers. I followed the quest marker to where I was supposed to meet Louis (a little north of Riften), and nothing. I can't find him anywhere. Do I need to wait for a certain time of day? I told Maven Black-Briar of the plot. Would that have an effect? I want to finish this quest.
UPDATED: So after fast traveling to a new city, to see if that would trigger him to show up, the prompt for Frost now says "Ride Frost" instead of "Steal Frost." Does that mean I can no longer finish the mission?