One of the quests generated by a quest map starts at a modest inn.  You enter the house, finds some corpses, track the wildling kidnappers, and rescue the victims who are supposed to join you as a pioneer unit.

If a pioneer unit joined my side, I did not see it.  I already had an unit of pioneers running around, and I had room in the army that cleared the quest camp. I think the reward is not properly given.  [edit] Now that I think about it, I am pretty sure that I failed to get the influence award as well, but i am not one hundred percent sure about that one.

I was playing a custom side with both Heroic and Wanderlust.