A.N. - Here it is, Chapter Fifteen! Sorry about the wait. -_- It's been a long and difficult year and it's not going to get much better (hooray for dissertations) but I'll do my best to update as regularly as possible. I hope you enjoy it. It's not a particularly long one this time, as Chapter Sixteen looks to be quite weighty.

Usual Disclaimer - Sirius Black, Severus Snape etc. are property of J.K. Rowling (even in death... -_-).

Chapter Fifteen

Cassandra awoke to darkness, damp and the smell of earth. Her first instincts were of panic and confusion. She fumbled around blindly in the dark, the tips of her fingers scrabbling for the touch of something familiar. Then she felt the warmth of the man beside her and heard the soft, muffled sound of his breathing. She smiled, chiding herself for her forgetfulness. Reaching into her robes, she pulled out her wand.

"Lumos," she whispered, and the tip of her wand burst into light. Holding it up, she could see little puddles of dried wax on the ground where her candles had obviously melted away overnight. The entrance to the burrow was still concealed by the ivy she had conjured, so she could not tell whether it was yet the morning. She decided not to wake Sirius. Instead, she stepped cautiously over him and, gripping her wand between her teeth, began to hoist herself into the narrow passageway to the surface. She discovered it was a little harder to wriggle out than it was to get in, as the tunnel sloped slightly upwards. When she eventually got to the leaf covered entrance and pushed the tangled branches aside, she was rather out of breath.

Dappled sunlight greeted her eyes. The forest was still and surprisingly serene, with the sweet melody of bird song the only sound Cassandra could hear. From the colour of the pink strewn sky that she could glimpse through the canopy, she guessed that it was not long past dawn.

"Where are you going?"

Cassandra jumped at the sound of Sirius' voice floating up to her from below. She slid back into the tunnel, replacing the leafy curtain, before she responded.

"I was just checking if there's daylight yet," she called back, as she wriggled her way into the little burrow. Just as she'd done the night before, she rather overshot the length of the tunnel and fell clumsily into the underground hollow. Somewhere in the darkness, she heard Sirius chuckle.

"Not funny," she muttered, as he began to laugh in earnest at her defensiveness. "Lumos!" she added, irritably, and a white light erupted at the tip of her wand, bathing them both in a heavenly glow.

"Good morning," grinned Sirius and Cassandra felt her annoyance melt at once. "And how is the outside world?"

"It looks to be just past dawn," the girl responded, returning his smile. She drew him into a warm embrace, noting sadly how his ribs protruded so from his back and how bony and sinewy his shoulders felt under her fingers. His hair, which she'd done her best to clean up last time she'd seen him, was once again matted with filth. As they pulled apart, Sirius met her gaze and flashed her an apologetic smile.

"It's been a rough few weeks," he admitted, quietly. "Rats aren't fantastically nutritious. Play havoc with my stomach too..."

Cassandra pulled a face.

"Rats?" she repeated, feeling nauseated at the very thought. "Is that what you've been living off?"

"Oh yes," he smirked fiendishly. "You have all this to look forward to! Unless you turn into a rabbit or something, then I suppose you can get away with living off grass and dandelion leaves."

Cassandra was reminded of the task ahead of them and she felt suddenly nervous. Transfiguration was not her strongest of skills – like any good Slytherin, her aptitude lay in potions and duelling.

"What if I can't do it, Sirius?" she murmured, looking shamefully at her knees. "Or worse, what if I do it wrong? I've heard all sorts of stories about wizards who can manage turning into an animal but they forget to retain their human memory. They forget they were ever human and live their whole lives as animals!"

"I won't let that happen to you," Sirius responded gently, placing a skeletal hand on Cassandra's shoulder. "James and I taught ourselves and we managed okay. If you're struggling with it though, we'll find another way. I don't want you doing yourself any damage."

Cassandra smiled at his words of encouragement.

"What's the plan then?" she asked, and the gaunt face across from her beamed.

"Well I don't know about you," Sirius murmured, "but I am starving. So I think breakfast first, then we can get down to work."

"I can't argue with that," Cassandra laughed and she followed Sirius out of the tunnel and into the forest above.

In the light of steadily rising sun, the little clearing looked rather pleasant and peaceful. Cassandra could not imagine why such a tranquil forest could ever be forbidden and she told Sirius so.

"It's not all like this, believe me," Sirius informed her grimly. "Let's just say the forest is out of bounds for a good reason. Now, if you'll excuse me for a moment fair lady, I need to answer a call of nature."

Cassandra blinked at him curiously and it wasn't until she saw him hitching up the front of his robes that she realised what he'd meant. She turned away at once, blushing profusely. Sirius simply chuckled

"Nothing you haven't seen before, babe," he called playfully, sighing his relief. Cassandra tried hard not to listen to the sound of him of him urinating. She focused very hard on the clearing around her, inspecting the trees and undergrowth for anything that might be edible. She spotted a small, if a little stunted, bush, which bore a meagre bounty of bilberries.

"I found breakfast," she declared, pointing at the spot a little way ahead of her. Sirius joined her a moment later, adjusting his robes.

"So you did," he grinned. "Well that will do for you nicely, and I can find something in seconds, this place is crawling with rats and hares."

"You're leaving me here?" Cassandra whispered, suddenly apprehensive. True, their clearing seemed safe enough but should some dangerous beast happen upon them...

"I won't be long, I promise," Sirius smiled gently, kissing her on the lips. Cassandra felt a tingle of excitement in spite of herself. "Keep your wand drawn and your eyes open and I'll be back before you know it. And make sure you eat – you'll need your strength."

Cassandra nodded, biting her lip as she watched Sirius transform into his dog form. He gave her hand a reassuring lick before bounding off into the trees, his tail wagging enthusiastically. The former Slytherin took a steeling look around the clearing. It looked as serene as it had done moments before but she knew better than to assume that this guaranteed her safety. Just as Sirius had instructed, she drew her wand and gripped it tightly as she bent down to harvest the little bush of its crop. The berries were small and sour and not particularly filling. Nevertheless, she partook of her frugal breakfast, trying not to think about the warm, creamy porridge or buttery croissants that she could have been eating back at the castle. Thoughts of Severus crossed her mind and she felt a pang of sickening guilt. What was he thinking right now, she wondered. Surely he must now know or at least suspect of her involvement with Sirius. Maybe, she thought with alarm, he might think she was dead. She felt a strangling urge to write to him and reassure him, which she berated herself for as soon as she'd thought of it.

Sirius was true to his word. He'd only been gone a few minutes before he returned, trotting into the clearing with his tail held high. He transformed and the big black dog became Sirius once again, who reappeared looking content and massaging his stomach.

"Rats and rabbits," he grinned. "What a veritable feast."

"Did you encounter any trouble?" asked Cassandra, as he sat down heavily on the leaf strewn ground.

"No," he yawned, lazily stretching. "In fact, the whole area looks untouched, which is good. At least we know the Ministry aren't running around looking for us."

He smiled at Cassandra, reaching over to toy idly with her glossy brown hair.

"Ready to get started?" he murmured softly and he looked her up and down thoughtfully. Cassandra gave a heavy sigh and the nervous, fluttering feeling returned to her stomach.

"About as ready as I'll ever be," she replied.

Sirius patted the ground next to him invitingly and bounced his eyebrows. Smiling uneasily, she settled herself next to him, ready to hear what he had to say.

"I suppose," he began, pensively, lying back to look up at the leafy canopy, "That the first and most important thing you need to know about the transformation is that it's not like becoming an animal. You don't need to think like an animal or act like an animal because, when it comes down to it, that's really what you're trying to avoid. It's more like putting on the disguise of an animal, because underneath you still want to be yourself.

"When James taught me, he told me to imagine wearing an animal skin over your clothes. Then, imagine the skin growing and changing so that it fits your body perfectly. Imagine it fusing with your skin, moulding to your body, and your body moulding with it until you look like an animal on the outside, but you're still you on the inside."

"But to do that, I need to know what animal I'm going to turn into don't I?" asked Cassandra, feeling flummoxed. "Do you just choose one and go with it?"

"No," Sirius smiled. "You already know your animal. It chose you."

"My patronus?" she gasped. "Of course!" It seemed obvious now he'd said it; she'd seen Professor McGonagall transform into her tabby cat form plenty of times and she knew from Professor Flitwick that her patronus was also a cat.

"Exactly," grinned Sirius. "So you would be a...?"

"A fox," Cassandra murmured, blushing. It was an intimate thing to reveal the form of one's patronus. Many wizards believed that it was a reflection of one's true character. If this was the case, what did having a fox patronus say about her?

'That I'm a crafty little rogue who kisses her colleagues behind her lover's back,' she thought instantly, but Sirius seemed to have devised another interpretation, judging by his smirk.

"A bushy tailed vixen," he chuckled. "How very appropriate!"

'You have no idea,' Cassandra thought sadly.

"Well, you know your target animal now," Sirius said, apparently checking a mental list off on his fingers. "You're aware that your own physical characteristics will affect your animal form, right? That charming little scar on your cheek, for example..."

Delicately, he traced the silvery line that ran the length of Cassandra's face with his thumb.

"I know," she nodded. "It will still be there."

"Luckily, scars aren't too noticeable on wild animals," Sirius counselled wisely. "It's if you had glasses or something that your disguise might be compromised."

Cassandra nodded weakly. So far, she didn't feel remotely confident. So she knew what animal she was meant to be turning into. She was no closer, however, to knowing how to do it.

"Is there an incantation?" she asked, hopefully. Sirius, however, shook his head.

"Sorry, princess," he smiled, apologetically. "It's like Apparition – you just have to learn how to do it." Cassandra sighed and shook her head.

"I must say, this seems an impossible task," she murmured. "But if we don't try, I suppose we'll never know how impossible."

"Remember the skin thing," advised Sirius, kindly. "I know it sounds ridiculous, but you'll be surprised how much it helps."

Cassandra and Sirius spent the rest of their morning practising the Animagus technique. Sirius, it turned out, was a patient mentor and for the entirety of the morning, he asked her only to familiarise herself with the form she was going to take on. He even disappeared into the forest in his dog form and returned with a living, breathing specimen for her to examine, which she quickly immobilised to avoid inevitable bites and scratches.

By the afternoon, Cassandra was thoroughly fed up of the sight of foxes, be they real ones or her patronus. She was delighted when Sirius decided to call it a day.

"I don't want to overload you to begin with," he smiled, as she threw her arms around him in an appreciative hug. "It'll only be detrimental to your overall transformation."

"What are we to do then?" she asked, curiously. "What do you normally do with your days?"

Sirius simply shrugged as he pulled Cassandra down to the ground with him and sat with her in his arms.

"I'll sometimes go scout out the school," he answered, thoughtfully. "Or I'll go to find the cat, he knows an awful lot about what's going on with Harry." Cassandra shot him a warming look and he added quickly, "I won't be doing that today, of course. I'll leave it a few days for things to blow over before I go back up there."

"Sensible," she nodded, leaning back into his skinny arms, surprised, as ever, by his strength. "So if spying and cat hunting are off the agenda, what is it that we're going to do with ourselves?"

The bony and ragged wizard behind her gave her bottom a frivolous squeeze, before leaning in to whisper lewdly in her ear.

"I can think of something."