Moonseed Poison
In the darkness, the castle seemed wild; all corridors and corners, deadly and alive and waiting to pounce. Hermione tried to silence her breathing from beneath the silvery folds of Harry's Invisibility Cloak, but the tension in her frightened chest made it near impossible. She had successfully managed to steal the cloak with a murmured 'Accio Invisibility Cloak!', but her success was only serving to irritate her conscience further. She had never been on a midnight mission without Ron and Harry's knowledge, and though she felt she had to do this alone, quickly, it felt wrong and almost shameful.
She came to the top of the staircase that descended into the dungeons, and looked down, strangely horrified. After a few steps her vision was swallowed by darkness, and even her ragged breaths were echoing off the stone walls. Hermione shivered, mentally gathering the scattered pieces of her Gryffindor courage, and started the slow, painful descent. Her unseen footsteps were repeatedly caught and thrown from surface to stone surface in the blackness. She swallowed and kept walking.
Finally, her foot met with even ground and, after an automatic inhalation of surprise, Hermione gingerly reached out a hand and groped through the cloak for the huge dungeon door. Her fingers met only air, even as she stumbled forward and forward. With a small groan of irritation, she frustratedly threw off the cloak and bundled it into a little beaded bag hanging from her wrist, and whispered 'Lumos!' The tip of her wand ignited and she looked upwards to see Professor Snape stood inches from her inside the open dungeon door, his obsidian eyes and hair lit by her wand and looking straight at her. With a shrill scream of terror, Hermione leapt backwards and fell over the final stair, landing with a crack of her head across the stone steps. Her wand flew from her hand, creating golden flashes and sharp shadows as it fell. The last thing she saw before her consciousness failed was Snape swooping, more bat-like than ever, towards her with those ever-unreadable black eyes widened.