Pierce is level-headed, stern, tactical, and a natural born leader who holds the team together. Helen mentioned that it was always Pierce who kept them grounded, and Pierce who always made sure they were careful.
As noticed by Helen, Pierce is the mirror image of Ben, both of them taking up the role of leader on their respective teams, and both of them being the calculative tactician who formulates the teams plans. On the first encounter between Ben's Team and the Plumbers' Helpers, where both teams end up quarreling with their counterparts, Ben, who is the only one without a mirror counterpart, breaks up the dispute by saying "Hey!! Stop it, all of you! What am I, your babysitter or something?!" which is exactly what Pierce would have said, which causes Helen to notice Ben and her brother's similarities.
Pierce is actually born as a human who was taken to the Null Void by Servantis. He used Kevin's powers and Argit to create Pierce's actual form. He, along with Helen, Manny and Alan formed a group, named Amalgam Kids and they were used by to do "nasty things". After they failed in their ultimate mission, their memories were completely wiped by Servantis.
Years later, Pierce became part of a team of young Plumbers apprentices, the Plumbers' Helpers, which included him, Helen and Manny. However, he was accidentally sucked by a Null Void Projector they had confused with a disintegrator weapon. He met Max Tennyson who trained him and helped him becoming a Plumber. Together, they protected the inhabitants from D'Void in the Null Void, gathering other Plumbers who were trapped/living there.
Unlike Manny and Helen, after sending someone with a Plumber Badge to the Null Void, he began to have doubts about what they were doing. However, before he could voice his concerns, he was believed to be killed when an attempt to destroy a DNAlien with the "Eradicannon" went wrong, this was later revealed to be false when the weapon they were using is shown is actually a Mark 1 Null Void Projector. In Voided, it was revealed that Pierce was stuck in the Null Void and began working with Max Tennyson to protect its inhabitants from D'Void, gathering other Plumbers who were trapped/living there.
He also appeared in War of the Worlds: Part 2 helping against the alien threat by the Highbreed and when the battle was over, continued in his task and became a pupil of Grandpa Max. He is also like the mirror of Ben Tennyson and often share the same views.
In Above and Beyond, Pierce acts as the leader of the Plumbers' Helpers on a mission to save Magister Max Tennyson from a rampaging Ben aboard a Plumbers' Space station in low orbit. Pierce is attacked by Goop. He is very respectful of Grandpa Max, usually referring to him by his Null Void alias of "The Wrench" or by his Plumber rank of "Magister". He is shown to be a capable leader who believes in working as a team. He often clashes with Manny over his leader position, mainly due to Manny's brash personality. He and his team manage to overcome their differences and work together to defeat Ben as Humungousaur. When they discover the space station they are on is going to crash into London, Pierce and the others realize the only way to stop it is to destroy the station before it enters the atmosphere. With their shuttle gone, Pierce and the others show they are willing to sacrifice themselves for the greater good. However Max appears along with Ben and reveals the space station is a Plumbers' Training facility and that Ben's rampage was actually a test for them. They are then told that because of their defeating Ben (as well as their heroic actions in trying to prevent the space station from hitting a major city) they are approved for training at the Plumbers' Academy and are sent to follow in the footsteps of their Plumber parents.
In The Purge, Pierce was shown wearing an ID Mask when on a date with a girl which is crushed by the Forever Knights who want him to leave Earth. He was later killed by them when he explained that he was unwilling and unable to leave.
Powers and Abilities
Pierce has the ability to grow thorns on his body. He can grow and retract them at will, as well as being able to shoot them as projectiles or break them off in order to use them as weapons.
Pierce is also highly skilled in acrobatics and hand-to-hand combat, regularly using them in combination with his powers.
Ben 10: Alien Force
- Plumbers' Helpers (first appearance)
- War of the Worlds: Part 2
- Vengeance of Vilgax: Part 1
- Above and Beyond
Ben 10: Ultimate Alien
- The Purge (first re-appearance; death)
Ben 10: Omniverse
- The Rooters of All Evil (first re-appearance; flashback; cameo)
- Weapon XI: Part 1 (flashback; cameo)
- Weapon XI: Part 2 (flashback)