Dr. Harry Carlyle is the medical doctor of Ark Hyperion of the Andromeda Initiative, and a member of Alec Ryder's Pathfinder team. Following the encounter with the kett on Habitat 7, Dr. Carlyle decides to remain aboard Ark Hyperion rather than returning to the field.
If Ryder responds to Captain Dunn's request for aid on a sensitive matter, Carlyle explains to the Pathfinder that one of his medtechs, Charlie, had secretly snuck his aunt, Ruth Bekker, onto Hyperion, past Initiative screening processes. And Ruth has a highly contagious, cross-species disease called TH-314, which remained dormant while in stasis until Charlie woke her up. Ryder's search led to Kadara, where it is discovered that angara are immune to TH-314 and Ruth had been captured by the Roekaar, who plotted to use the virus. Ryder sent Carlyle this information in hopes of eventually creating a cure or at least a vaccine.