Chaimson was a S.H.I.E.L.D. agent assigned to the Hub. During the HYDRA Uprising, he worked with Agent Victoria Hand to maintain the security of the Hub against HYDRA. While transporting the HYDRA infiltrator, John Garrett also known as the Clairvoyant, he was murdered by HYDRA sleeper agent Grant Ward.
Agent Chaimson was one of five other agents that Victoria Hand knew was not a HYDRA sleeper agent and had pledge his loyalty to S.H.I.E.L.D. He was at the Hub when she gave the order to kill Phil Coulson's team and John Garrett when they would arrive there aboard a reprogrammed Bus.
When Victoria Hand tested the loyalty of Jemma Simmons and Antoine Triplett, she threatened them with death if they were not HYDRA agents. Triplett took Chaimson and held him at gunpoint, threatening to kill him in response, believing he was a HYDRA agent. That response caused Triplett and Simmons to pass her test, proving their loyalty to S.H.I.E.L.D.
After revealing himself to be a HYDRA agent, John Garrett was to be transported to the Fridge by Agents Chaimson, Jacobson, Hand, and Grant Ward. Chaimson was killed by Agent Ward aboard the Jump Jet.
- S.H.I.E.L.D. (First Incarnation)