Rose has to stifle a giggle when she sees it: the Doctor's clumsy grope for Jack's hand, Jack's utterly startled look. Jack's immediate reaction, so unexpected, defensively drawing back, as if he thinks that he has somehow accidentally caused their fingers to meet. The Doctor clears his throat, pulling his hand to his side, trying to pretend nothing's happened. The outer curves of his ears are slightly red. "This way," he says, hurrying ahead.
And then Jack lunges forward, takes the Doctor's hand. The Doctor looks back, smiles. Jack smiles too. They hold hands, awkwardly.
Rose turns, hiding a grin.