Ex Meridian by A.E. Via

A brutal, heartless, assassin’s way of showing his partner/lover a romantic Valentine’s Day

Take a man and strip him of his ability to feel compassion, empathy, remorse…love, any of the emotions that make him human, but leave the ones that ignite rage and aggression and you have the perfect killing machine—now imagine two of them.
Code names Ex and Meridian are synonymous for ‘guaranteed death. Two men recruited into an unsanctioned government program and trained to operate most efficiently—lethally—together. Without the risk of lust or love getting in the way.

Until something within them changed.