Garrison follower Harrison Jones is a unique Follower in 6.1 WOW, although its' quality only at rare. A lot of players become very interested in Harrison Jones because of his unique Traits and his vibrant performance in the previous expansions. 
The two important Traits:
Mentor: Accompanying followers gain the Follower's combat effectiveness. The skill can temporarily upgrade the level and item level of Followers who play together in a team to the same standard of the user.
Treasure Hunter: Increase the gold gained from a mission by 100%. 
The mentor is a high ability to upgrade low-level follower to a high level, which can fast level a lvl90 Follower to lvl100. In the late game, Followers are general with Treasure Hunter ability. You can form a treasure army soon by Harrison Jones, match the gold mission in Level 3 Lunarfall Inn(A)/Frostwall Tavern(H), you'll find that wow gold suddenly becomes much easier. It is no wonder that Blizzard will weaken gold mission in Garrison in the next expansion.
Harrison Jones will publish daily in your Garrison when you upgrade Garrison to level 3. Doing the daily is the only way to unlock Harrison Jones. You will gain achievement Don't Call Me Junior and Harrison Jones after finished this series of missions. The quests are random refresh in the garrison hall, if your Garrison quest didn't update, you need to go to friend's garrison or Looking For Group to find the quest.
You can get Harrison Jones in few days if lucky, then to recruit treasure army freely. Harrison Jones is going to be the best person to promote new Followers.