A/N: This is getting tough! Not only is this the longest fic I've written, it's the only really complicated one...things are getting messy. I'm not entirely sure where it's going to end up – you may have to request a plot so it doesn't slide into PWOP. I'm not too keen on that option – but I am lazy, and hassled. My creative brain has had a hard time of it recently. I apologise. Mind you – here's Severus again, so be happy.

Severus Snape was not having a good day. Ordinarily he would have told himself sardonically that this was nothing out of the usual. He couldn't even remember having a day he'd describe as 'good'. Today it appeared that even the most sympathetic of the Fates was against him.

Once again Potter had confirmed his belief that the boy's very existence was the cause of all his suffering. If Potter had died like any self-respecting normal person Voldemort would not have gone through this metamorphosis, but instead have been hunted down and killed. Severus had no doubt that his own metamorphosis owed little to Potter's survival, but he resented the fact that due to that outcome, he himself was still alive. Had he not experienced such a change in conscience, he would certainly have been killed, fighting for Voldemort. Matters had been so much easier when you believed utterly in your cause. Doubt was far worse than death, the agony more prolonged and cruel than any torture Severus had known in his long and terrible experience.

Occlumency with Potter was agonising. The boy was utterly useless at it, but had the uncanny ability to reverse the spell so that he saw into the mind of the one who cast it. Voldemort enjoyed exploiting this ability in order to manipulate him. Severus instead found his innermost mind invaded and those carefully buried memories uncovered as Potter blundered thoughtlessly through his psyche. Potter had in fact gone out of his way to do so, poking into the pensieve while his back was turned, demonstrating a complete disrespect for Snape's seniority and privacy. Now he had learned of an experience even worse than Severus' most humiliating memory. Now Potter knew exactly to what depths of darkness Severus had sunk, worse than what had been done to the Longbottom's, worse than the killing of Cedric Diggory, worse than what Ginny had been subjected to, worse than his own personal tragedy.

Potter had seen the definitive event of Severus' life. The event so horrific, so evil that it had turned Severus' mind inside out and caused him to question everything that he had believed up until that point.

There had been a girl, a muggle-born girl in Severus' house and year at Hogwarts who, despite everything had always tried to reach out to him. Like him she was often ostracised, persecuted for being the only 'mudblood' in Slytherin. He had always participated in this, venting his own frustrations on her to compensate for the injuries inflicted on him by James and Sirius. A few years after he left Hogwarts and embarked fanatically on his vocation as a follower of Voldemort, he encountered this girl again.

Voldemort had always been keen on experimentation. One day Lucius dragged in the cowering form of a young woman and, in reference to a newly discovered parchment on Summoning, proposed an investigation.

The results were truly terrible. Severus could remember the expression on her face as she recognised him. It had had no affect on him in the heat of the moment, but now it cut him to the core. They had summoned a high demon, cut her living heart from her body and allowed the demon to take its place. She was neither dead nor living, human or demon. The mindlessness of the demon drove her mad and the smallness of her life caused the demon unbearable hunger. After savouring the sweetness of their achievement they had dumped the spent body into the street.

Only later did Severus realise that what they had done was only at the tip of the iceberg that was Voldemort's capacity for evil, and he could not stomach it.

This was what Potter had seen through the eyes of Severus' memory. This is what he had forced him to relive, to remember the pleasure, the justification he had once felt in committing such acts. By the end of it, he had been close to vomiting he was so sickened by his past self. Potter had not been able to say a word as Snape stumbled away from him, gagging, doubled up and weak with despair and disgust. The boy's eyes had been utterly blank, his face expressionless as he turned mechanically to leave

Snape kneeling, trembling with shock on the unforgiving stone of the floor.

Severus knew he had a stack of holiday homework assignments to mark, but following this unwanted dredging up of a deeply sensitive matter, he had to see Dumbledore.

Albus was pacing in his study, deep in conversation with the new Minister for Magic, Helena Evander, a retired Order member and a very pragmatic, practical woman. As Severus entered her head craned out of the fireplace to see who it was. He noted the change of expression and decided something was afoot.

"Albus – I simply must dash...meetings and all, you understand?" Helena strove to make a quick exit look less like an escape.

"Yes quite right my dear. I shall speak to you anon."

The Minister's head vanished from the flames and Dumbledore pivoted to face him.

"I have seen that look before," Severus began but was cut off before he could begin to speculate on the new burden the ominous cast of Albus' face suggested.

"I must urge against your immediate resignation on this latest revelation. Despite everything it means you know as well as I that the past cannot be revoked and that we must face our demons rather than run from them."

Clenching his jaw, Severus steeled himself against what he was about to hear. Special weight had been given to the words 'past' and 'demons' despite Albus' every attempt to keep his tone quiet and even.

"As you know, the post of Defence Against the Dark Arts has yet to be filled. A possible candidate has presented herself, but I believe you should be consulted before she becomes part of the staff. She will be arriving in a minute or so."

"Albus," Severus fought to subdue the moth-like emotions that were sending tremors through his veins, "Albus, who? Why...why? Albus, Potter knows about..."

A tower of flame erupted from the fireplace between them and Severus felt his heart freeze within his chest at the sight that branded itself into his disbelieving eyes.

"Isla Kittson..."

The figure of a woman Severus thought had died fifteen years ago was emerging from the diminishing Floo fire. She straightened up. From her eyes Severus could see this was not the same cowed victim he had known, these eyes were not the eyes of any normal human. They glowed, a subtle, otherworldly shifting gold.

"Severus Snape." This too, was not the same voice. Severus was transfixed by its unnatural resonating purr; it washed over him, curling around him as if tasting him. Before he had even realised it, her face was inches from his own. She breathed in. Abruptly Severus realised his muscles had turned to water and she was draining the strength from his limbs. As suddenly as she had begun, she released him.

"To be honest I don't care what you did. Yes, it was beyond Unforgivables, yes it was unjustifiably wrong. However," she gave a rueful smile, "You ultimately created a means to send Voldemort straight to the deepest circle of Hell."

She paused, considering, "I am no longer the person that existed before my life was tied to  , the unnamed demon you dragged into this world and imprisoned in me. My life, so to speak, did not end, but I now exist as neither human nor demon.

At first we could not coexist, that is what you saw. The demon could not escape and I could not die while it lived in me. We have survived together since by feeding from the life energy of others; I know I can spare you the details of that.

'You owe me nothing, or rather you owe us nothing. We have both undergone a transformation. All that matters now lies in the future."

She stepped back, refocusing her attention on Dumbledore, who, sensing the potential for a pregnant silence, decided to break it before it happened.

"Miss Kittson, Hogwarts of course welcomes you back. It is we who are indebted to you for offering to join us and offering your unique expertise which shall no doubt prove invaluable to both the students and the Order."

The new professor raised her hands, "Please, spare me the formalities. The most important thing for the present is that I may introduce myself and explain my peculiarities. The students may have had strange DADA professors in the past but they will not appreciate my authority if they are left to work out my nature for themselves. I would rather not be taken for a mere succubus or a vampire."

Dumbledore could not resist a chuckle and glanced up at the intricate clock on the wall between the portraits of two past headmasters who, under the pretence of sleep had been earwigging on everything that had just happened and were itching to spread a bit of gossip. The hands had just clicked into place to read half-six and a jolly peal rang out as a legend began to form across the dial, 'Dinner Time'.

"Well, there's no time like the present. After you, professor..."

Severus dumbly followed in their wake. He was numbed, unable to comprehend fully what he had just seen and heard. Was it just a figment of his imagination, a manifestation of his guilt? A person, thought to be, expected within all reason to be dead had just reappeared into his life on the day that the bloody Potter boy had decided to crash through the exact memory of her supposed murder.

Severus Snape was not having a good day, and he had no doubt that this run of strife was to continue. After all, he had a feeling he was due to be summoned by Voldemort in the near future about the impending initiation of Draco Malfoy.

Dear god this is getting messy! Oh well...mess is what I do. I hope this isn't too extreme for you – it will come together I promise. Again I have noooo idea when I will have time to do the next chapter. Review, review, review...