Canary
They had barely set foot in the cold, barren hall when they were stopped by McGonagall. "Ah, there you are," she said sternly. 'Mr. Potter, Mr. Weasley... both of you will have detention this evening."
Ron and Harry had wit enough not to question her as they were told where the detention would be. Harry tried to get out of detention with Lockhart but was dispelled by the firm 'No' from McGonagall.
The next morning was spent listening to Harry whining about Lockhart. Draco tried his best to console Harry, but he was a little preoccupied by a slightly tired-looking Ginny.
Draco stayed as non-threatening and innocent as possible. He branched out and asked for help from the Twins. After a whole three days of vigorous brainstorming and strategic planning, Mission Canary was initiated.
It started slowly like all good things. A quill writing in yellow instead of black, the bed curtains turning a gold yellow, pillows going yellow, and one of the robes turning yellow mid-class.
Little palm-sized canaries would appear out of nowhere. Curiously enough, only Montague was able to see those canaries.
After a couple of days, canary pictures started popping up on his clothing. First, the jumper, then the shirt he was wearing, his books, and every conceivable print or picture on his person turned into a canary. However, as soon as the item was removed from his person, the items would turn back into normal objects.
Montague tried blaming Draco for this. He even tried going to the Head of the House, Snape, but nothing stuck to Draco. For one, Draco never came into contact with Montague to curse or hex him. Secondly, all the evidence brought to Snape was curiously hex, curse, or spell-free and stayed normal, hence the grievous snubbing Montague received from Snape.
In the next couple of days, Montague started "bleeding" yellow. (Not literally.) Everything that Montague touched or came in contact with would turn a bright yellow. His lackeys and friends started moving away from him as a couple of them turned yellow after shaking hands with him.
The finale, however, came on the next Friday, a week after the 'yellowmania' started. Curiously enough, Madam Pomfrey was on leave for urgent matters, a once-in-a-million chance coincidence.
As the buzz of breakfast started in the Hall, Draco and the Slytherins had joined the Gryffindor table once again, but instead of eating breakfast (except for Ron, Greg, Vince and Neville), they were busy looking (more like staring) at Montague. Partially due to the eye-scalding yellow ensemble he was in and partially in anticipation.
Just after Montague had a couple of spoons of that extra yellow scrambled eggs and yellow toast, his words turned into tweets. By the time he left his seat and reached the middle of the Hall trying to go to the faculty table, his skin started shining a bright yellow, and in less than two minutes, Montague was turned into a human-sized yellow-skinned, red-beaked, human-canary hybrid with feathers and all but with hands instead of proper wings.
And that’s how Montague spent three days at the end of September in the Hospital wing, tweeting for the whole time, as Pomfrey and Snape looked into breaking the undetectable curse or hex. That was also how Draco and the Twins received a week's worth of detention. But it was worth the look of dread that fell on Montague's face on seeing yellow color, thereafter.
The next week or so was a blur of activities, what with detention, classes, and Draco teaching Harry about finances and the benefits of having legal counsel. They asked McGonagall and Snape for any solicitors that might be good.
Draco asked Narcissa for a list of potential solicitors, and that ended in an hour-long Floo call with Draco assuring Narcissa that everything was fine and no, he was not looking into emancipation, no, he had not gotten into any misadventures or troubles, and it was just for Harry to get his legal matters organized.
Somehow, despite all this chaos, Draco finally found time to reach out to a slightly confused yet readily accepting Luna. It was easy enough to convince everyone of their distant relation as cousins. Pansy took to Luna faster than anyone. They would be seen often together or with a sallow-looking Ginny.
Thus, they became a gang of eleven on regular days and twelve when Ginny joined them. At this rate, they would need enlargement charms for the train compartment to accommodate all of them, but Draco was sure they’d make do, somehow.
Draco had asked for a list of private investigators from Narcissa as well to find Remus Lupin, but was denied when she found out that it involved Snape. She didn’t want to be ‘an accessory to Snape’s broken heart.’ (A little late for that, mother.) Hence, Draco’s failed attempt at hiring an investigator.
In all this excitement, October arrived unnoticed, spreading a chill over the grounds and in the castle. The faculty, staff, and students were facing sudden cold spells (not actual spells), and Pomfrey was overworked.
Ginny was starting to look paler and fragile. Shockingly, Draco and Percy came together quite well in taking care of her (as much as he could in Draco’s case).
As the weather turned colder and rainfall started turning every space muddy, Oliver’s enthusiasm for training never dampened. Draco became Proficient and Expert in many shielding, sheltering, and warming spells.
A week before Halloween, Draco & co., with their new additions, were invited to Headless Nick’s deathday party, which honestly Draco had forgotten about but would have regretted if he had missed. It would have been 'really not fun and an utter travesty,' according to Luna, who was sitting between Pansy's legs on the floor getting her hair plaited by Pansy.
It took a couple of days' worth of discussions and debates to finalize which costume they would be wearing (suggested by Draco to Hermione's surprise).
Neville, Theo, and Blaise were going as a Norse God Trinity (Draco had no idea whom exactly, but their dresses were seriously hot). Pansy and Luna were going as Day and Night, and Ginny was joining them as the Blood Moon. Draco and Harry were going to be The White King and The Red King of Hearts. Vince and Greg were Tumbledee and Tumbledum, Ron opted for some famous Quidditch captain while Hermione wanted to be the stereotypical witch from muggle tales.
All in all, it was going to be an epic Halloween.