She should not to be confused with Hartley's deceased grandmother, named Vivian Winterbottom.
Her son, Hartley, was recruited for a covert op and given the codename "Agent X". Stephen Bartowski engineered a cover identity for Hartley, who was not a field agent, and implanted the cover by creating the Intersect. The Intersect was used by him to gain deep government information and profiles on people he suspect could lead to bigger events. Eventually, the Intersect overwhelmed and corrupted him, making him lose all memories of who he actually was, causing Hartley to truly believe he is his cover identity; Alexei Volkoff.
As Volkoff, he founded Volkoff Industries and became the world's most illegal wanted arms dealer. Mrs. Winterbottom is aware that Stephen had gone AWOL from the CIA since then and had spent his life trying to retrieve and repair her son. It would, however, appear that she is unaware of the entire covert op her son was working on, as like other spy projects, it was classified. This would mean that she has no knowledge of where her son is or who he had become.
John Casey loves her, her heavy machine gun, and grenades, and describes her as "like the mother I never had". Mrs. Winterbottom is action hero material, taking on, and out, a group of mercs who assault her home with a machine gun concealed in the coffee table and then a grenade and some C4 to finish them off.
She comments her son was much like Chuck, not comfortable with guns.