He watches her yawn as they sit in the library, his eyes are immediately drawn to her mouth and he smiles to himself. He watches as she applies candy flavored chap stick and he laughs as he realizes that it's cherry and that just last week he told her how much he loved that certain taste. It was nice to know that she remembered such small things; it is those ideas that mean the most to him.
Remus believes that Nymphadora tastes like heaven. This is quite a thing to use as his choice of description, for if she knew, it would be a lot to live up to each time they kissed. As of now he has not told her, it's his own private secret that keeps him smiling as he remembers when he's sleeping on the cold, stone floor of the underground after a day of trying reconnaissance.
Sometimes when they're sitting at home on the couch he'll bring up a subject that he knows she enjoys speaking on just so that he can listen to her. She will ramble on and on about music, Quidditch or infiltrating muggle bars (each of which he is no expert on, so he usually doesn't need to interject his own opinions, merely watch her gesticulate animatedly and smile). At night she will whisper to him before they sleep, she tells him about her day, how much she cares for him, little things. He delights in those most of all.
What completely blows him away is when he's returned from an especially harrowing transformation and she's standing there waiting for him. She murmurs how he will be alright, and how she is going to help him, and every new scar he has obtained for various reasons receives a gentle kiss. He wants to cry then, sometimes his eyes even do glaze over with years of unshed tears, but he doesn't want to upset Nymphadora; the fact that someone would want to be so close to him knowing what he is is astounding enough, but to feel her gentle, calming lips on his scars, something that he himself professes to find grotesque, is enough to make him wonder (and worry) if this is not really real, or if he actually is so lucky to have this incredible woman for his own.
Unlike her loud appearance, when she speaks to him she's very quiet as if she's afraid she might wake herself up from the dream that is her relationship with a certain werewolf. He likes this for it shows that she does know how to be mature despite her exterior, it gives him a sense of reassurance that she means what she says and that she would never go back on her word. She could tell him anything and a part of him would believe it; but when she tells him she loves him, his entire being is filled with joy that he should be so loved, and the grief and self-hatred that have made their perch on his heart slowly begin to melt away.