River had to admit to himself that he hadn't expected her to say that, but he didn't mind it at all. And true, he could spend time with her best friend, obviously, but he was going to keep wondering how long this flirting was going to go on. He didn't know how he felt about that yet. Regardless, he gave her hand a squeeze when she took it and said such a thing, showing that he appreciated her saying that. Maybe the proper thing might have been to say she was attractive too, but... not in front of Derek. "I'm sure, as long as y'all can handle a little music." His west Texas accent apparent in that sentence.
Derek had taken the liberty of stretching his legs out in the back seat, trying to get comfy. Hell, he could sure as hell sleep.