Here is a little missing moment type HBP story I put together. I might post it in the FAP challenge forum later on.
It's set just after Harry ran into Tonks in the corridor at Hogwarts. It's R/T without Remus actually being present...
Cross Purposes
Tonks stumbled down the corridor, making no attempt to stem the flow of her tears, barely able to see where she was going.
"Ouch!"
She stopped, a far off look on her face. "Is that you?" she asked desperately. "Are you ok?"
A dreamy voice drifted up from the floor: "Oh, yes," it said, "it's definitely me."
Tonks looked down, surprised. "Oh, I'm sorry. Did I knock you over?"
"Well, yes, but that's ok, You probably didn't see me because you're crying."
Tonks coloured. "Uh, erm... do you want a hand getting up?"
"No, I'm fine. I quite like it down here where no one can see me."
Tonks surreptitiously brushed the sleeve of her robe across her eyes, and squinted at the girl on the floor to check for signs of sarcasm. She saw none.
The girl met her eyes. "I know you," she declared. "You're Nymphadora Tonks."
"What? Yes, that's right," Tonks agreed vaguely.
"You're an Auror, and a member of the Order. I wouldn't mind being a member of the Order," she added, "I liked being a member of Dumbledore's Army last year."
"You know Dumbledore?" asked Tonks, her attention refocusing.
"Well, yes. He is the Headmaster."
"Did he tell you anything about the Order members? About who got hurt-?"
"No. But I'm sure he's fine."
"He is? Oh! You mean..." Tonks' gaze drifted off into space once more.
The dreamy voice interrupted the silence. "I saw you at the Ministry. I know why you're crying."
Tonks jumped. "You know?" she asked incredulously. "How do you know?" She lowered herself onto the ground opposite the ethereal looking girl, and stared into the silvery eyes with rapt attention. "It's Luna, isn't it?" she enquired enthusiastically.
"Yes. It's me, Luna. But shouldn't you ask me a harder question?"
Tonks looked at her blankly.
"To prove my identity?"
"Oh, right. Um, I don't know much about you. Wait, got it! Do you know Remus Lupin?"
"Of course. He was at the Department of Mysteries, and he taught Defence against the Dark Arts in my second year. He has very clean teeth. I like him much better than Professor Snape, don't you?"
"Much." agreed Tonks, her eyes once more filling up with tears. "He's the -"
"You're crying again," interrupted Luna.
"I know."
"It must be hard for you."
Tonks sighed wistfully.
"Daddy wants to write an article about it."
"About - ?"
"Your situation."
"Your Father knows!"
"Oh yes."
"And he's going to write about us?"
"You won't be named specifically. Unless...well, you could give him an interview if you want. That's what Harry did last year, and it worked out very well for all of us."
"I can't do that! This has to be kept as low-profile as possible, he hates the spotlight. If I did that he wouldn't even speak to me, never mind - "
"It could look better for you, if people know you're at least resisting it..."
"What? I'm not resisting it! He is! I don't see any problem, but he won't let me-"
"Well, I must say, I think he's right, whoever he is, and I'm glad someone's resisting at least. Just one person could-"
"You...think he's right? But why? I refuse to accept that he's dangerous!" Tonks shouted.
Luna's orb-like eyes fixed upon her, as though sizing her up. "Oh dear, you've got it bad. No wonder you're crying."
"Oh, I have!" Tonks said sadly. "It's upsetting my powers, interfering with my work. I can't think about anything else!"
"Of course, it's not surprising. Vampires can hypnotise people into doing what they want, without even using Imperius," Luna rationalised.
"What! He's not a Vampire! He's a werewolf," Tonks retorted, scandalised. "And he would never-"
"Oh no, he's not a werewolf. I know a werewolf. Very nice man. But Scrimgeour? Definitely a Vampire. No one but a Vampire could control the Umgubular Slashkilters."
"The what, now?"
"You don't even know about the Umgubular Slashkilter? But it's central to the Rotfang Conspiracy, it's the only thing that can spread gum disease without self-infection -"
"You what...?" Tonks exclaimed, realisation slowly dawning. "Wait, your Father runs The Quibbler, doesn't he?"
"- They're impervious, you see. No teeth," Luna continued. "What was that? Oh, yes, Daddy edits The Quibbler. He tried to run this story once already, but some people," she said weightily, "want the truth to say hidden."
Tonks maintained a stunned silence.
"I know," Luna exclaimed. "It's shocking."
Tonks climbed to her feet, shaking her head and staring into the distance. "I thought she really knew," she whispered.
"Oh, but I do know," Luna declared.
"Why I was crying?" Tonks asked sceptically.
Luna nodded fervently.
Tonks turned to leave, a befuddled expression on her face.
"And if it's any consolation," Luna called after her, "if you were to put fluoride in the Ministry water supply, I'm pretty sure Professor Lupin would love you back."
The End