Summary: Tonks sneaks down to the Dungeons one night, and unexpectedly meets Snape in his grey nightshirt ... Will he help her brew the potion she wants? SSNT, Extreme fluff warning. Complete.

An Encounter

Nymphadora Tonks sighed with relief as the door to Snape's office finally opened. She had spent a good hour trying get in if you counted the time it had taken her to find the place, and since she was only spending one night here at Hogwarts, she would have to finish what she was doing before the students came here in the morning.
She glanced at the empty corridor behind her before she went inside, but it lay dark and deserted just as it had done when she first came. She realised that it must be well after midnight by now, so she hadn't got much time.
She went straight over to the store cupboard to get what she wanted, but on her way there she accidentally knocked down a huge glass jar from its shelf, which exploded with an enormous crash, spilling a glutinous, sickly green liquid all over the floor.
She groaned. Always so clumsy, how tired she was of it. Why couldn't she manage to do something well for a change? Without making a mess of things? But it couldn't be helped; she would have to get on with it. She started to clean up. Ten minutes later, she decided that she had done enough and, finally, went over to the cupboard.
'Looking for something in particular, miss Tonks?' a cold voice came from behind her just as she had found what she needed. She gasped and turned around. There, dressed in a grey nightshirt, stood Severus Snape. 'I do apologise,' he added with a sneer, 'I didn't mean to startle you ...'
'P-professor Snape,' Tonks stammered guiltily, 'er – I didn't know ...'
'Didn't know I was back from my mission?' Snape said softly. 'And thought you might have a look in my store cupboard while I was out of the way?'
'N-no, it's just that ...' she looked down at her feet. How was it that Snape still made her feel like a Hogwarts student after all these years? 'I needed to make the Draught of Peace, and I didn't have all the ingredients ...'
'The Draught of Peace ... You'll need some syrup of hellebore for that ...' he took out a small, dark bottle, 'and some powdered moonstone ... There you go, Miss Tonks.' He looked at her, his cold black eyes as inscrutable as ever.
'Oh, thanks,' Tonks said, smiling, feeling a little less intimidated. After all, she was a member of the Order now and not a student, so at least Snape couldn't take points from her house for what she had done. 'Then I just need a cauldron,' she said, wondering if she was being too cheeky for old Snape. He, however, kept his poker-face and went to get her what she'd asked for, putting the cauldron and the ingredients on the table.
'There you are, Miss Tonks,' he said, looking at her with interest. She began measuring ingredients, lighting a fire beneath the cauldron with her wand. 'Oh, blasted thing,' she swore as she knocked the cauldron off the table, the flames spreading to some parchment nearby. Snape extinguished them at once, looking a little annoyed now. She felt nervous again, and managed to drop the bottle of syrup of hellebore on the stone floor. She could feel her face go pink; syrup of hellebore was very expensive, she knew.
'Oh, I'll make it for you,' snapped Snape, 'I don't want you demolishing the place...' He moved quickly but graciously as he added the ingredients, stirring when necessary. Every now and then he threw her a glance through curtains of shoulder-length greasy black hair. What was he thinking? Wasn't he even wondering why she wanted this potion?
He was good at it; there was no denying that. Tonks leaned forward to look into the cauldron, where the potion had now thickened nicely. Snape was leaning over it too, obviously having to concentrate quite hard right now; she knew this was a difficult potion to make.
She didn't know what made her do it. Perhaps it was his mouth, his lips slightly parted in concentration, or maybe it was the way he looked up at her when he'd added the last drop of syrup of hellebore (he had gone to get another bottle instead of the one she broke).
Whatever it was, it made her look back at him properly for the first time that night, yes, perhaps for the first time ever. Why had she never noticed the smoothness of his skin before, and the length of his eyelashes? Or the intensity of his gaze, and the shape of his mouth?
Then everything happened automatically: his fathomless black eyes seemed to draw her closer to him, until she could feel his breath on her lips, warm and sweet. And then she kissed him, just as the potion began giving off light, silver steam, which encircled their faces. She kissed him quickly, shyly, as if she regretted it half-way through – which, come to think of it, she did – this was her former Potions master, after all. She couldn't possibly want to kiss him – nor would he want to kiss her ...
'That wasn't very convincing, Miss Tonks,' said Snape in barely more than a whisper as she broke away. She looked at him. What did he mean? Had he – did he – had he wanted this? He walked over to her side of the table, his arm brushing against hers as he reached over to the cauldron again, stirring three times clockwise, then turning back to her, eyeing her scrutinisingly.
'I'll show you how it's done,' he said, lifting his hands from the cauldron and taking her head, holding it gently but firmly, drawing her close again, then kissing her. To her amazement, he was good at it – very good. She could have gone on and on kissing him the whole night. Yes, that was what she wanted to do.
Slowly, hesitantly, she put her arms around him, responding to his kiss. A long, black strand of hair fell into her face, but she liked it; she didn't mind. His hands were warm and soft and very gentle, caressing her as if she had been something very fragile. Nobody had ever treated her like something fragile before, clumsy as she was ...
As she felt his bony shoulders beneath the nightshirt, she wondered vaguely what sort of life he led, down here in the dungeons, going on dangerous missions at more or less regular intervals. Did he have any family? She had never asked.
Then Snape straightened up, looking at the cauldron again, still holding one arm around her. 'The potion is ready now, Miss Tonks,' he said softly as he withdrew his arm. 'Shall I fetch you a bottle to put it in?' She nodded.
Snape filled the bottle, then gave her the potion. 'Use it with care,' he said, his eyes glittering strangely.
'I'll see you at the next meeting, I expect, Professor Snape,' Tonks said, grinning.
Snape raised an eyebrow. 'I daresay you will, Miss Tonks.'
She left the dungeons, still smiling to herself.