This just popped into my head after seeing something related in a board on 4chan. Blame them for this, not me.

Rin glared at the woman across from her, again, and took a deep breath.

"So," she began, her voice wavering almost imperceptibly. "So, you're absolutely sure that my mana transfer isn't working?"

The blonde woman nodded precisely and made a soft affirmative sound. Her blue-green eyes did not rise from the floor between them.

Rin swallowed hard. "Are you sure…"

"On a knight's honour," said the blonde woman in a soft, but firm voice. "I have no reason to make up such a thing, Master. That would be meaningless."

"You say that now…" Rin set her cup down on the table and leaned back in her seat a little more. Her head tipped back to rest against the back of the couch and she stared dimly up at the ceiling. "What an inappropriate situation. I had thought that with my magic expertise, you would be the most powerful Servant of all. But now I can't even recharge your mana reserves for even simple self-healing."

"It is not your fault, Tohsaka-san. Perhaps I have not been performing my duties properly?"

The dark-haired magician waved one hand dismissively, grinning across the table at her Servant. "That's just nonsense. Ever since I summoned you, Saber has been nothing but the perfect Servant. With your help, I can surely defeat any other Master, no matter how powerful they are."

The blonde woman dipped her head slightly and said nothing, her expression firmly neutral.

"Well…if I am still unable to channel mana into you the usual way…"

Saber looked up suddenly, a hint of confusion behind her eyes.

"There is…one way…" Rin rubbed the back of her head as she blushed. "But that's just silly. I mean, it sounds like some perverted manga or something…"

Saber blinked, clearly oblivious. "If this is the only option left," she said a little more insistently than before, "then it must be taken. Without my mana, I am of little use as your Servant, Tohsaka-san."

"Well…it's just…it…involves…er…" Rin made some very vague gestures with her fingers and fidgeted a little in her seat. Saber looked none the wiser from any of it. Although she did notice, eventually, that Rin's eyes were slowly drifting up and down her body. Such an intense look, as if the young magician girl was peering straight through her blouse…

She gasped. "No! Not…th…that!" Her face was flushing slowly and there was a somewhat desperate look in her eyes as she spoke. "That would…that would be…"

"It seems that it's our only option, unfortunately," replied the magician, averting her gaze so that Saber couldn't see her own blushing face. "I'm…sure that…it'll…be fine, really. I can devote my time to…research, to find some other way. Something more…well…reasonably, at least."

Saber blinked. "But…how do we…I mean…" She clenched her fists tight at her sides and glared down at the floor. "How…do we…well…that is…"

"You don't…know?"

"Of course I…" the blonde woman began, then trailed off. "Just…not with… I've never…with another…"

Rin stood up quickly, determinedly. "Then I'll teach you! Or rather," she corrected hastily, red-faced, "we can learn together! So that you can regenerate all the mana you need…"

Saber sat on the very edge of the bed, her legs hanging off the end and folded to one side with her hands resting neatly in her lap. Her eyes were focused intently on the floor just in front of her, and a deep scarlet flush diffused through the smooth, pale skin of her cheeks. Her body was taught and tense, and trembling in the very slightest.

"Are you…are you ready?"

She decided not to look up and nodded her head just a touch, her lips parting to an almost inaudible noise of affirmation. There was a sharp click, and the light in the room died, leaving her illuminated only by the faint moonlight seeping in through the thin curtains. A palpable sensation of anxiety crept through the air, as if the whole room was holding its breath, as if the surroundings themselves were waiting for something to happen.

Soft, muffled footsteps padded across the floor towards the bed, slowly, cautiously, almost hesitantly. There was a ruffle of cloth as clothing was shed, piece by piece. A dark, pleated skirt fell to the floor with a whuff and delicate, black stocking-clad feet stepped out of the cluttered remains where it lay on the wooden floor.

A hand touched her shoulder. Saber looked up, diffidently, and found a startlingly beautiful female face gazing raptly down at her. Tohsaka did certainly look different by moonlight.

Rin held her other hand up, but it wavered and hung in midair before it reached its intended destination. "This is just…" Saber swallowed again. "Because…because we have no other…no other way of…of…"

Rin cupped the blonde woman's cheek, and she fell into a stunned silence. She stayed that way as her Master leant down over her, until their faces were so close that the blonde was forced to lean back…

…Rin followed her motion, gaining ground in the process. In no time at all, their lips met. It was clumsy, uneven, sudden; a faltering first kiss. Both girls froze for a moment afterward. Rin's hand on that lightly clad shoulder trembled. Before she knew it, her fingers were loosening the buttons on the Servant's blouse with the ease of long practice on her own garments. Her conscious mind seemed to rush away from her all at once as she leaned in again and stole a second kiss, undeniably more passionate than the first.

Saber stared at her reflection. It stared back, wide-eyed. It looked a little shell-shocked, for want of a better word.

"That," she muttered in a voice that was far steadier and calmer than she felt inside. "That…was…just…"

"I'll start researching as soon as possible," interrupted Rin nervously. "I'm sure there's a…more agreeable way for you to draw mana."

Saber turned and stared at her Master. That was probably a bad idea; her Master was still practically naked and didn't seem aware enough to cover herself from the blonde's gaze. Saber felt her cheeks reddening again and breathed deeply.

"Just…the once…"

Rin looked up at her. It was an ominous look.

"Unless," she said quietly, "I can't…find anything useful."

Both women looked back towards the bed. An uneasy sort of tension gathered between them in the space of seconds.

"Are you sure you're feeling all better now?" she asked in a voice that was revealingly monotone.

Saber wetted her lips with the tip of her tongue. "Ah…perhaps…I have not fully recovered yet," she replied in the same almost dead tone of voice. "It would be better to…to make sure…that my mana reserves are…f...full…"

Rin took her by the hand and swept her across the room like a strong breeze brushing leaves across the ground. Moonlight streamed in through the still-open window and gave the whole room a more romantic, otherworldly feel.

The third kiss was better than the first two. By far.

This doesn't mean nothing, honest.