Being with Christopher is easy. He's always nearby. He knows about Everworld. He knows about the Old World. He's been with David every step of the way, and whether he was willing or not, that means something. There aren't many people David feels on the level with. There aren't many people he trusts. There aren't many people who understand him. Which is flattering, on the one hand, and dangerous, on the other.
April is too rooted in thou-shalt-not-kill rhetoric (which apparently doesn't apply when your sister's a crazy witch, though technically God recommended a stoning, not a stabbing) to be comfortable with David's war-mongering ways. She's too much of a bleeding heart. No matter who she plays on stage, no matter what face or part she adopts, she's still too easily swayed by the morals of the life she left behind. If she knew all the things David does, she wouldn't be able to look him in the eye.
Jalil is too stuck on numbers, paring the battles down to lost and won, how many dead, how many wounded, how many new uniforms and pairs of boots and swords. David wouldn't have gotten this far without Jalil. But to Jalil, he's another commodity too. A symbol of the war, a General who's a decent tactician but mostly a morale-booster. His men would follow him to hell and back – which is lucky, since that's where he leads them half of the time.
To Christopher, he is just David, the same things he has always been. A target for mockery, a drinking buddy, a bed-warmer when there is no one else or he's too tired for flirting or he just wants the comfort and ease that someone you know can bring you. He's one of the few parts of the Old World that are still here in Everworld. Christopher is all about comfort, not in that he's high-maintenance or needs a lot of things, but in that he likes the familiar. He likes faces he knows and food he knows and things that remind him of home. There's a chronic homesickness he can't shake, even though he says he doesn't want to go back. David helps.
And David understands that. There's comfort in easy things, familiar things. It's nice to know all the ropes. It's nice knowing exactly where he stands. With Christopher he knows exactly what he likes and doesn't like, what he is and isn't into. They've got it down to a routine, when they sleep together, something that works for both of them and doesn't need any fixing.
When Christopher sneaks into his tent, David doesn't even wake up anymore. He knows the pattern of Christopher's footsteps, the sound of his uneven breathing. He knows the slight dip in the bedside, the first hesitant touch to his shoulder blade. It's hard and fast and satisfying, the both of them always back in their respective beds before morning. It's easy, but that's not why he does it. To David, easy is weak. Easy is copping out. Easy means it will end sooner or later. Easy means nothing.
Because when he looks at Christopher sometimes, he gets a tight feeling in his chest. He thinks about all the things he'd risk, all the things he'd do, all the choices he'd make if it came down to it. If he had to. He thinks about the people he'd betray, the ideals he's squash, the promises he'd break. He thinks about dreams and nightmares and enemies and friends and what he can afford to keep.
And that's not easy.