Starfleet security officer and Maquis leader, Eddington served as Starfleet Security's liason aboard DS9. Much to Constable Odo's chagrin, Eddington represented a different kind of justice and protocol than what Odo was used to.
During a mission to save Odo from the clutches of a Cardassian-Romulan Alliance en route to destroy the Founders' homeworld, Eddington was under Vice Admiral Toddman's orders to sabotage the Defiant should Sisko take it to rescue Odo in defiance of the admiral's orders.
Upon Eddington's reveal as a member of the Maquis, Sisko vowed to capture his traitorous former officer, although the two eventually formed a deep, mutual respect.
IA romantic, Eddington died in 2373 saving his wife and Sisko from Jem'Hadar forces.