His expression didn't change very much outside of the occasional brow raise and chuckle when a particularly amusing scene played on the screen. Presently, Marlin was busy chiding Nemo about his inability to stand on his own two feet (figuratively, of course) while Nemo accused him of being afraid of the ocean and past experiences. It was ridiculous that he should feel a kinship with the older Clownfish and see similarities in the argument between father and son and the recent turbulence in the already complicated relationship he shared with Rose. Did she think he was too overbearing, too deeply rooted in his own ancient ways to see beyond his own point-of-view? He hadn't exactly asked what she might have wanted before leaving his double in her care. Hadn't seen anything but the black and white--the gray area always seemed to be missing anymore.
Honestly, was he really comparing the lives of cartoon fish to his relationship with Rose? He would have allowed the exasperated breath to blow and bubble between his lips with a decidedly self-deprecating roll of his eyes were he not afraid Rose might take notice. They were supposed to be enjoying themselves, watching a bloody children's film and having a lark, but instead he was too busy playing the brooding old Time Lord to give it a proper chance. Maybe this hadn't been such a good idea, after all.
The Doctor needed to relax, if not for his own sake, then Rose's at the very least. She'd been through enough for one day, she didn't need to worry about where his head was on top of it all. So it was, without warning, that he slipped a hand to the outside of the couch and pulled the small wooden lever, abruptly causing the section of couch they were presently lounging upon to recline with a clatter from neglected metal springs. If he was going to loosen up those tense muscles working overtime inside his head, he might as well get comfortable first.