Heheh. This is me rationalizing my way out of canon via stupid one-shot. Enjoy!
And if I hate the canon, I obviously don't own the books. That Rowling woman does.
Tonks glared at Remus silently from across a puffy couch in The Burrow. He just couldn't like himself enough to let her love him, could he? She turned the other way and stared viciously at a handmade rug instead.
"Nymphadora…"
"Just shut it, Remus. You might be older than I am, but you could still be my mother's son. Being poor is absolutely no reason to lock yourself away, and I'm an Auror, for crying out loud! You're a puppy compared to a death eater." She scowled and turned to him. "I know you're enjoying your little Tortured, Misunderstood Man shtick, but I for one think you deserve to be loved." She immediately regretted saying that, but she wouldn't admit that if her life depended on it. "I do love you, Remus. Don't you care about me?"
Remus had been sitting in silence, staring at his worn shoes as he thought about what to say next. "Tonks, please let me explain this properly. I know I should have done so a long time ago, but… I loved Sirius. We were in love ever since we were in Hogwarts, and I can't imagine being with anyone else. Forgive me for not telling you sooner."
Tonks stared slack-jawed for a moment, before spitting out "Y-you're a pouf? And Sirius, too?"
"In so many words. Hadn't you ever noticed before? We didn't exactly hide ourselves, except around Harry and his friends."
"Well… I suppose that does make sense. Sitting in his lap in front of the fireplace seemed a bit chummy, even for old school friends." Tonks noticed a pained, reminiscent expression on Remus's face and thought it would be tactful to change the subject. "Well, I don't know what to think now. I suppose that's a much better excuse than the old-poor-dangerous spiel… Do you like me at all?"
Remus paused and studied her face carefully. "You're a marvelous girl, Tonks. Sometimes your sense of humor even reminds me a bit of—" he swallowed and bit his lip, "—of Sirius. But my affection can never be more than platonic. I-I'm sorry."
"Couldn't you have just said that from the beginning? You get frightened of some of the most imaginary things…" Despite her harsh words, she looked considerably less angry, and not quite sullen, either. "Maybe you could just be my shopping pouf?"
"Do I look like a shopping pouf to you?" Remus gestured to his robes, almost smiling.
Tonks burst out laughing. "I suppose not… Couldn't I look after you, though, Remus? It isn't as though we couldn't be chummier. You're so… I think Sirius would have liked to know that someone was there for you."
"He…" Remus choked up suddenly, but continued talking with determination. "One of the first things he told me after Azkaban was that he worried about me every day in that cell." He smiled weakly. "I'm not too good at taking care of myself."
"I'd have to say that everyone's noticed that. I'll do my cousin proud, don't worry!" She grinned from ear to ear. "I'll hound you with food like Molly does to Harry."
So, that's why they hold hands. Remus is still totally faithful to the late Sirius Black. See? See?