Nalya Battlehorn

Nalya Battlehorn is a tauren that can be found in the Town Hall in Frostwall once the Garrison is in Tier 3.

She offers players a chance to purchase unlocked follower contracts that were not available as quest rewards due to divergent quest lines, or having a choice of one among several followers.

For divergent quest lines, the only other way is to change the zone outpost to access the questline that you didn't do the first time around.

Quotes
Greetings, commander. Some willing recruits may still wish to join our garrison. I will gather the contracts for you, so that you may peruse them at your leisure.
 * Gossip