Ooh, really lovely; intriguing blend of comfortable and bleak. Which perhaps this pairing should be. There's no way they'd have an easy time of it, at least not in the beginning.
I like that there's so much unspoken understanding between them: "Draco chuckles, and his smile calls Ron a liar" and "He catches the glitter of mischief in gray eyes a second before Draco sweeps his tongue out, curving it beneath the head of Ron's cock." Ron watches Draco so attentively throughout this scene. It's really the actions, not the words, that speak the loudest here. Short, subtle, and poignant.