Civilian Master — Cassandra Carr

Originally released as part of the Unconditional Surrender bundle in 2014, now available as a stand-alone novella complete with BRAND-NEW 5,000+ word, 16-page short story.
The only life Clay Benson has known in years is the Army. Now he's on forced leave after a Ranger mission goes terribly wrong. When he decides to return home, Clay knows he needs to face his past, and the only man he's ever loved: Flynn. Now Flynn is a Dominant, and Clay wants nothing more than to heal and find his true self. Is his place as Flynn's submissive? Flynn certainly thinks so, but must convince Clay there's something worth fighting for besides his country.