Author's note
Thanks for reviewing! My mother tongue is Italian and my fiction has already been posted in the Italian section. I'll try to speed up my translation work. Back to the story. There's so much to tell…

That night sleep eluded her like a crumple-horned snorkack. Six years before, when she had left the school of Witchcraft and Wizardry, Iris had sworn she wouldn't set foot in there again. Too many memories wriggled in the twist and turns of her mind. Slimy, chaotic… A nest of snakes that snapped at each other with fratricidal fury.
She had started with the same enthusiasm as any young witch. Her parents, both naturalists, were rather famous in the Magic world. Well-known, brilliant and, what counts most, Pure-blood. As an only child, Hogwarts had marked her first, real attempt at socialization. Learning the laws that ruled this new universe turned out to be harder than expected though. Youths' naivety and fickleness, their occasional cruelty disconcerted her. Used to live in the reassuring world of adults, she soon found herself looking for their company also inside the school. Teachers, charmed by such an unusual personality, kept their labs doors open well beyond class times. As for her, Iris found more challenging the disquisitions about the properties of Professor Sprout greenhouse's plants than the sickening House rivalries or the soppy gossip about the last Quidditch hero.
The Sorting Hat had long wavered, brooding over the apparent contradictions of her mind. After a nerve-racking soliloquy, it had eventually called 'Ravenclaw!', never stopping grumbling out its doubts. Iris was greatly relieved not to be obliged to wear Slytherin's or Gryffindor's uniforms. She despised the slightly dumb boldness of Gryphons as much as the unbridled ambition of Salazar's adepts. In Ravenclaw she could sharpen her mind, concentrating on the ultimate answers nature and magic were keeping for her. That's how it was for seven years. Bright student, blameless -well, almost- conduct. But for that young, newly appointed Potions Master. Her personal auto-inflicted torture.

Her first teaching day welcomed her with the exhausted hug of a sleepless night. Perhaps she had bit off more than one can chew. One week before, when she was told Professor Sprout was looking for an Herbology assistant, her clearness of mind had crumpled like a bewitched house of cards. She had to know. She had to understand. She had to go back to the place where all the answers were possible. Where everything had started and really never ended.
Her first reaction, while reading the vacancy ad on The Daily Prophet, had been one of astonishment. Why on earth Madam Sprout was looking for an assistant four months after the beginning of the classes? Whatever the reason was, her puzzlement had soon given way to the untamable fire that still burnt in her chest. She had sent her CV through howler and in four days' time confirmation of her employment had flown back on the wings of a white owl. Timing had not surprised her. She suspected hers was the only application sent to the school. Nevertheless she was somehow annoyed by the bureaucratic banality of such a course, in times that all were but banal. Not to mention the sign at foot of the convocation... A small, nervous handwriting read: The Headmaster, Professor Severus Tobias Snape.

One hand up shook her out of her random thoughts. She observed the second year students and bitterly realized that every sign of enthusiasm had vanished from their faces. Suspicious looks darted all over the greenhouse as though they were expecting some kind of ambush. Sad and creepy, she mused, how fear and sorrow can transfigure a youth feature into that one of an adult…
'Yes… Blaine, if I'm not wrong.'
An olive-skinned boy, with big dark shadows under his eyes, nodded curtly.
'Professor… Madam…'
'Professor will do, Blaine.'
'Professor, you said the extract of mandrake is the most powerful antidote against petrification.'
'Correct, Blaine.'
'And petrification can be caused by indirectly gazing at a basilisk.'
'Right.'
'Is it true a basilisk hid in a secret chamber, right here, in the castle?'
Several pupils dilated as if darkness had suddenly fallen.
'True. But it was killed,' professor Amberlin replied trying to reassure the most impressionable ones.
'Professor,' the boy's voice lowered to a whisper 'Potter killed it, didn't he? HARRY POTTER.'
Her eyes rushed worriedly to the entrance. She bit her lower lip and silently cursed her momentary weakness.
Fear is getting pandemic...
'Yes, Blaine. Mister Potter,' she said pronouncing clearly the name 'killed the basilisk during his second year at Hogwarts.'
'It's a good thing, isn't it?'
'Sure it is.'
'Then why?' the boy's voice rose in pitch 'Why the Prophet says he's a wanted criminal? I mean, one doesn't get evil all of a sudden, does he?'
An inner smile fought its way up to Iris' lips. But she restrained herself. Had some Slytherin reported to the Carrows, her career could have well come to an end right before starting. If not her life…
Not bad, Blaine. Not bad…
'The border between good and evil is often unsettled, Blaine. Our motivations are only known to ourselves… and I wouldn't even be too sure about that. Some actions look inexplicable or evil simply because we lack pieces of information. Anyway, to answer your question,' she sighed 'no, I don't believe one can get evil all of a sudden.'
A slow, measured applause broke the excited murmuring that had spread over the greenhouse. Dozens of heads turned around abruptly towards the source of the disturbance and immediately withdrew, pressing against professor Amberlin.
That man had a wicked taste for sensational entrances. Sinister maybe, but memorable. He looked down at the class with unreadable eyes, hands still mocking an applause.
'I don't believe the propaganda for a fugitive is included in the Herbology programme,' he hissed.
'Headmaster Snape, I…' but she was cut short.
'Remarkable speech indeed. Should I decide to set up a chair of rhetoric, I'll keep it into account. Now, professor Amberlin, if you please, your students are eager to be introduced to the fascinating mysteries of…mandrakes?' he added mellifluously and with an elegant twirl of his cloak he disappeared in the courtyard.
Son of a…
'Now folks, wear your earmuffs and prepare all you need for repotting BUT do not touch mandrakes until I'm back! Got it? I've to…uh, settle a matter. Five minutes, not longer. Blaine, you are in charge.'
She barely recorded the boy's bewildered look, then rushed out of the greenhouse, her wand tightly clenched in her left hand.