Ian MacLeod is the brother of Donovan MacLeod. He is a resident of the Prime Universe, and lives in London on Earth. He is a few years older than his brother Donovan, and therefore escaped Centro Systems' most vigorous attempts to recruit soldiers for the War for Mars. The war was starting up just as Donovan was graduating from high school, but since Ian was already in college at that time, he was not recruited. He entered law school instead.
When his brother returned home from the war, Ian focused on trying to help Donovan readjust to civilian life. He suggested that Donovan should form a PTSD support group with his veteran friends. Donovan did start a support group, but he also started an activist group, the Working Class Heroes, which he coerced Ian into joining. Ian was reluctant at first, but joined when Donovan promised him they were not doing anything illegal.
At Donovan's suggestion, Ian became the legal counsel for the group, and he focused on making sure they didn't cross any "too dangerous lines." Under his guidance, the group stayed peaceful, and all of its founders stayed out of jail. He also advised them through several of their first major victories as a group.