James thinks the main reason he's able to love Lucy so much is because she looks so little like the rest of his family. Her hair is the colour of smooth chocolate, and her eyes a dark, midnight blue. It helps him forget for a minute that they are family.
But it gets harder when she speaks, when she laughs. She throws her head back the same way his mother does, and her voice has the same smooth lilt as his Grandmother's.
So instead, they don't speak. They touch and kiss to fill the silence. It works, in the end.