The Scanner (also known as Subroutine XXLDWR) was a Machine program designed to track humans who have ingested the red pill, but have not yet been extracted by Zion. It was revealed that the Machines eventually discarded the program, and thus became an exile.
It is believed that the exile appeared in Chapter 4.2, where he allied with the Cypherites in trying to hinder EPN's effort to recruit, by finding an killing them.