Despite his employment, Simeon was not a Vesper, but had worked for the group prior to the Rosenbloom break-in. He had been hired by syndicated, cartels, and dictators in the past for other criminal activities, including murder and torture.
In preparation for breaking into the Rosenbloom residence, Simeon used a long-range microphone to spy on Mark and Jake Rosenbloom. Once he thought the house was empty, he jammed the cell phone signal nearby and, with two Vesper agents, began drilling into the front door of the house. His plans were altered when Dan Cahill and Atticus Rosenbloom noticed his presence and activated the security system. Simeon broke into the house, but was attacked by Atticus before he could reach Mark Rosenbloom's study. He chased Atticus with his Cretan dagger, and cornered him and Dan. Moments before he could kill the boy, he was attacked by Jake, and sprinted away from the house as the police arrived.
Simeon is a sadistic individual who takes pleasure in breaking things and people, and wields a beloved Cretan dagger for such a purpose. Along with the dagger, Simeon displays a knowledge of ancient history. He is also a gruff and angry leader who belittles his subordinates.