Loyalty
Heat was great, of course. He was full of energy, always willing to do it hard and fast, on the floor, bent over a table, pressed against a wall, anywhere, anytime, wham bam thank you Leader.
Sometimes, however, it wasn't what Serph wanted. At those times, he turned to Gale.
He didn't remember when the first time had been. Time before Sera seemed all compressed together because everything was the same, and time after her seemed so short because everything was changing. He did remember the hows, though. How Gale's droning voice had suddenly sounded soothing to his ears. How he had wondered how Gale's long fingers would feel on the skin of his back. How Gale's face, sharply lit by the light of his map, had seemed... nice. Beautiful, even, in the darkness of the room, and Serph couldn't really remember thinking of anyone or anything as beautiful before. It seemed like an odd thing to think of Gale, but these were odd times.
Gale had not flinched when he had touched his hand, fingers lightly brushing over plans to ambush Harley. When he had touched his broad chest, Gale had merely asked if he wanted to call it a night and go to bed. Serph had nodded, then looked at him expectantly. Gale had seemed to understand, as ever, dull grey eyes deciphering Serph's thoughts as easily as he read his maps. Without a word, he had followed his leader to bed.
He had not looked at him any differently while lying back on his bed. He had let Serph peel his uniform off piece by piece, even helped Serph out of his own. He had reciprocated when Serph had held him in his arms and caressed him, learning his strategist's body, drinking in his warmth.
And when Serph had taken his cock in hand, sat on it and began moving, he had done his best to meet Serph's thrusts. In bed, as in life, he had not questioned Serph's judgement at any point. Guided it yes, doubted it, never.
So when Gale confessed he wanted to serve him always, no matter their future incarnation, Serph knew he was the most likely of his men to be true to his words even beyond death.