Khalophis was born on the world of Prospero, and joined the ranks of the XV Legion, newly renamed the Thousand Sons, after they were reunited with their lost gene-sire. He was a member of one of the earliest intakes of potential Neophytes. The first time he appeared in recorded history was when he served with the Iron Warriors, a Legion he admired and ranked second only to the Thousand Sons. As part of their training, all Captains of a Thousand Sons Fellowship undertook a secondment to another Legion to learn its ways and further the Thousand Sons' understanding of the galaxy.