Damon was a technician for the High Council of the Time Lords who worked in their records section.
Like all Time Lords, Damon was taken from his family at the age of eight for the selection process in the Drylands. Staring into the Untempered Schism as part of a Time Lord initiation rite, Damon was inspired by what he saw in the Schism. (A BriefHistory of Time Lords)
Damon gave the Fifth Doctor proof that a member of the High Council had stolen his biodata extract, which had allowed Omega to carry out his plan to achieve physical existence once more. Damon helped The Doctor by reassembling the Heart of the TARDIS after Maxil had removed it. (Arc of Infinity)