500 more words. You can find the beginning
Here.
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2:30am and Harry found himself sitting (in pinstriped pajamas, no less) in McGonagall's office. The baby rested quietly against his chest. They were waiting, and it wasn't long before the potions master strode into the room, closing the door sharply behind him. He didn't even look at Harry.
"Minerva. What could possibly be so important?" Sallow hands clutched his nightrobes around him tightly. She made a curt gesture in Harry's direction and whatever barbed reply Severus had in mind got caught in his throat.
"It's his potato." She snapped.
"It's a girl." Was all he could get out.
After a few moments of explanation, Professor Snape conceded that, paired with certain charms, a wash of armadillo bile could probably cause certain side-effects.
"It's conceivable," he said as he sunk into a chair. "Armadillo bile is the active ingredient in wit-sharpening potions."
Harry was careful not to speak, and instead watched Snape with interest. At the moment, he hardly looked cross or callous, very different from how Harry usually saw him. His black eyes glinted with the crisp intensity of deep thoughtfulness. Professor McGonagall leaned over her desk and examined the infant in Potter's lap. Her face creased with concern.
"Will it undergo anymore changes? Can you come up with an antidote?"
"With some time, yes, I believe I could concoct a reversal. And I don't think it will be undergoing anymore transformations." He paused and shot an almost hesitant glance at Potter and the creature. "It looks stabilized."
Harry couldn't help but purse his lips. Certainly the circumstances were odd, but it was still just a baby. They were treating it like one of Hagrid's monsters. McGonagall exhaled in relief.
"Well, until the time that this can be reversed, I'd feel more comfortable if the child was kept under close observation."
Severus nodded in agreement. "I'm sure Potter will be able to handle it. After all, he's had so many dangerous adventures, I can't fathom an infant causing him any trouble." He was clearly taking pleasure in Harry receiving the burden of more work because of an accident.
"Actually, I meant you Severus. You can't possibly think I'd leave a young life, whatever it is, in the hands of a student." The satisfaction drizzled from his face as she continued. "You'll be best equipped to handle the situation if things go awry."
Harry wouldn't abide by this. She couldn't leave the poor thing alone with Snape! He probably put her in a box. Besides, it was his project, his responsibility. He spoke up.
"I'd like to help, Professor McGonagall."
The woman looked as surprised as Severus. "Well, Potter...yes, I suspect Professor Snape will be needing some assistance." As she spoke, Harry was certain he heard a dry bemusement underlining her words. "You will both be responsible for the child until this is all sorted out."
"I'm sorry," Snape interrupted. "Did you say 'sorted' or 'sordid'?" His anger and disbelief rang clearly in his quip. McGonagall matched his dangerous tone.
"Don't get scrappy with me, Severus." A wirey finger waved at him. "This is a most unfortunate situation for all of us."
But most of all for Eloise, Harry thought. That is what he had already named her.