Shrub works with his partner Pockets Possum as couriers. They call themselves Pockets Postal Service.
Shrub can only says, Me are Shrub, much like Groot's "I am Groot".
Shrub was created by Filipe Andrade and Skottie Young for their run on Rocket Raccoon & Groot.
Major Story Arcs
Tricks of the Trade
For more information see: Rocket Raccoon & Groot: Tricks of the Trade
One day Groot hired the Pockets Postal to deliver him to Lord Rakzoon. Upon making the delivery, Pockets and Shrub were accused of being thieves and thrown in Lord Rakzoon's torture dungeon.
After making a deal with the imprisoned former dictator of the planet, High Ruler Nosaj, both Pockets and Shrub tried to have Rocket and Groot killed; however, their plan backfired after their squabbling caused Nosaj to decided to have all four killed instead. The quartet escaped the palace, but Pockets still held resentment towards Rocket for imprisoning them, and almost getting them killed. Rocket responded by stealing Pockets' ship, leaving Pockets and Shrub stranded.