Ethan Locken was a doctor, and worked as a pediatrician on New Beijing. At some point during the Dominion War, false intelligence was given to the Dominion that biogenic weaponry was being developed on New Beijing. The Dominion sent the Jem'Hadar to wipe out the planet; Locken was the only survivor, having found a safe place to hide by Doctor Murdock, who was undercover Section 31 operative Cole. Following the destruction, Locken was recruited by Section 31, realizing the need for such an organization.
In the closing days of the war, Locken was assigned to investigate a Jem'Hadar hatchery on the planet Sindorin in the Badlands, where Section 31 hoped to create a breed of Jem'Hadar loyal to the Federation for use in any upcoming conflict. For the first few weeks, Locken reported in at regular intervals, but then became sporadic and eventually lost touch. Locken had discovered a way to produce Jem'Hadar loyal to him, and betrayed Section 31 to follow his own gains, intending to provoke a war between the Federation and the Romulan Empire.
By the time Bashir was assigned by Section 31 to hunt down and neutralize Locken, he was in his 30s or 40s, and had short cut red hair that had receded into a widow's peak. He was neither tall nor physically imposing, but his eyes were a dark brown or almost black color.
Locken was, by any account, a brilliant scientist. He used his genetically enhanced abilities to work on medical advances in long-term statis, cloning, DNA resequencing, memory engram transfer, and other similar pursuits.
While Bashir distracted Locken, Ezri Dax was able to damage his equipment on his space station headquarters so that his attempt to attack Romulus- framing the Federation for the attack- failed. Locken was subsequently torn to pieces by his own Jem'Hadar, whose DNA had been slightly altered to remove their loyalty to him. (DS9 - Section 31 novel: Abyss)
In a timeline where Khan Noonien Singh had won the Eugenics Wars, Locken served in the Earthfleet and was noted as a fellow Princeps and rival to that of Jullian Bashir by the Lord Sisko of that dimension. (DS9 novel: Seeds of Dissent)
|Known members and associates of Section 31|
|Primary universe||Julian Bashir • Lance Cartwright • Cole • Dietz • Matthew Dougherty • Sarina Douglas • Franklin Drake • Enderby • Darwyn Friel • Harris • Jedburgh • Bendes Kettaract • L'Haan • Peter Lawrence • Ethan Locken • Roberta Luke • Merra • Erovan M'Rill • Tinh Hoc Phuong • Erik Pressman • Malcolm Reed • Tomas Roeder • William Ross • Connaught Rossa • Luther Sloan • Aubin Tabor • Malla Tancreda • Charles Tucker III • Vasily Zeitsev • Cortin Zweller||31|
|alternate reality||Thomas Harewood • John Harrison • Robert April • Alexander Marcus • Yuki Sulu • unnamed Section 31 operatives|