Find The Guy Sitting In The Tree House (On Map 1) And Pay Him Some Coins.
1. He Tells You He Needs His Trophy And He'll Join You.
2. Find His Trophy! It's On The Map Somewhere, Stuck In Some Rocks. Grabbing It Spawns Some Greed So Be Careful!
3. Bring His Trophy Back And He Joins Your Quest
Achievement Pops When He Gets Out Of The Tree. He Has A Bike Charge Attack That Goes Through Walls, It's Pretty Helpful.
Good Luck!