Twins' Brains, Snape's Gains, Umbridge's Pains
Fading to Black
Unfortunately for Snape, the Twins didn't give him the antidote to the GBGB directly. Snape spent the first day in his chambers, and the second, only coming out on the third day after a threat from Madam Pomfrey and Professor Dumbledore. Needless to say, they were both gobsmacked by the latest turn of events. Well, at least Madam Pomfrey was shocked, he mused. Dumbledore had merely chortled, offered him a lemon drop, and said that at least male and female professors had the same title.
Now he was fuming anxiously. He had chosen looser black robes than he normally did, but it was obvious that he had the body of a female. Worse, he had the first years of Hufflepuff and Ravenclaw later today and the Gryffindor and Slytherin second years tomorrow. And Dumbledore had expressly forbid him to cancel his classes to find an antidote. He had the respect of the older students, or at least their fear. He didn't have that for the younger students.
Put shortly, this wasn't going to be fun. Especially since all of the ready-made antidotes he had on hand didn't seem to have any effect, and it was definitely something not to waste a bezoar on. Too damn expensive to replace for something less than life-threatening.
The first class he had was sixth year NEWT students. Perhaps, he mused to himself, the older brats are worse than the younger ones. Indeed, the sixth years sniggered and snarked and snorted about him when they thought he couldn't hear them. To them, it was amusing. It made him want to give each and every one of those little over-dramatic gossip-mongering dunderheads their own Gender Bender Gummy Bears. In the end, he had taken 70 points from Ravenclaw, 50 from Hufflepuff, 30 from Gryffindor (due to the fact that while he had multiple students from all the other houses, he had a single Gryffindor in this class), and gave detentions left and right (with a few extra to the Slytherin miscreants in private, since he didn't want to take points from his own House.)
By lunchtime, Snape was seething with hatred, humiliation, and a thirst for revenge. That in mind, he decided to skip lunch in the Great Hall and take an impromptu trip to Diagon Alley to visit a certain set of especially trying twins.
Three small bells chimed in the shop door, heralding Snape's entrance. The twin that was minding the storefront looked up. First, his eyes came across the oh-so-lovely chest hidden by a black robe. "Well, milady-" And he cut off once he reached the head, particularly the face, attached to the chest he had only moments ago held in such esteem. The black eyes were no longer fathomless as they remembered from school, instead glinting with anger. A fire that only burned brighter after his aborted statement.
"Turn. Me. Back." A voice that was not quite Snape's growled from what was clearly Snape's angular visage.
Infuriatingly, the twin grinned up at the teacher's fear-inducing countenance. "Georgie!" He shouted at the backroom. "Sneering Snape's here already! Pay up!"
Before Snape could ask what they meant by 'already' or give some other irate statement to the twin that turned out to be Fred, as his glare did not seem to adequately express his feelings of utmost ire at the situation and the twins' antics, George appeared. "Already? I'd have thought that he would have tried making his own solution first."
Snape lost his composure. "Not without having any idea of what ingredients you used, you imbeciles! Now, change me back."
George gave three sickles to Fred, ignoring the outburst for a moment. Then they turned to Snape. "We'll give you the antidote-"
"If you will allow us-"
"To take a few pictures-"
"Before and After pictures-"
"So that we can show everyone-"
"Just what our new product does-"
"So, what do you say?"
Snape groaned, acquiescing after a quick glance at his watch. He had fifteen minutes before his next class, and it took seven of those minutes to get down to the classroom. He wanted to be his correct gender before dealing with the incompetent, destructive dunderheads that comprised most of every class he'd ever taught at Hogwarts. No more than the first years' first Potions lesson. "That is acceptable, if you give me the antidote, and a...confection. You'll get your pictures, but I will not be dragged into being in them."
The twins glanced at each other, coming quickly to a decision.
And that was why Dolores 'Damien' Umbridge spent several days as a male. Everyone thought it was a time-delayed prank left by the Twins before they left. No one noticed that Snape snitched one of Creevey's pictures of the humiliation in the ensuing chaos.