One evening after detention, Alexander gathered Cho and the twins.
"I'm teaching you three a new spell."
Fred leaned forward immediately.
"Explosive?"
George added:
"Illegal?"
Alexander shook his head.
"Better. Invisibility."
All three froze.
From then on, every night after detention, the four of them met inside the Room of Requirement.
Alexander demonstrated first.
His form shimmered — then vanished into the background like a living reflection.
The twins circled where he'd been standing.
"Brilliant…" Fred whispered.
"Terrifying…" George added.
At first, they struggled badly.
Fred turned half-transparent but still glowing.
George's hair stayed visible, floating midair.
Cho flickered in and out like a faulty lantern.
Alexander corrected wand angles, incantation pacing, and magic output control.
Night after night, they practiced.
Weeks passed.
Gradually—
They improved.
Not perfect yet — outlines still faintly visible if you looked closely — but functional enough for stealth movement.
Alexander nodded in approval.
"You'll master it eventually."
During these weeks, another change happened quietly.
His friendship with Hermione evolved.
He no longer called her Ms. Granger.
Now it was simply Hermione.
Whenever she had academic questions, she'd run over during meals.
Spell theory.
Homework optimization.
Study structuring.
If Alexander felt like answering, he would.
If he didn't, Cho would step in and explain instead.
It became an unspoken system.
Alexander also noticed something else:
The Gryffindor trio had reconciled.
Hermione, Harry, and Ron were back to being friends again.
Kids, he thought. Troublesome but predictable.
With Halloween nearing, Alexander and the twins entered full planning mode.
Final prank inspections began.
Supply checks.
Trap placements.
Alexander already had most materials stored in his briefcase.
The twins were still inventing additions daily.
They also ensured one key ally was ready:
Peeves.
The castle poltergeist received:
Amplified stink bombs
Screaming parchment scrolls
Auto-firing ink balloons gun
Corridor echo charms
His new favorite toy.
Fireworks that followed students like a missile and exploded.
Doesn't cause any damage, but enough to scare students.
Peeves cackled with delight.
"The Evil Ghost shall rise again!"
Alexander only smiled.
To secure operational freedom, Alexander joined the official Halloween Decoration Committee.
It granted him:
After-hours movement clearance
Decoration placement authority
Access to the Great Hall
So instead of Detention Alexander and the twins would set up decorations.
He even personally requested additional décor support from Hagrid.
Pumpkins.
Enchanted vines.
Fog barrels.
Hagrid happily delivered oversized versions of everything.
By the last day of September:
Disillusionment training: operational
Peeves: fully armed
Prank routes: mapped
Escape paths: tested
Decorations: enhanced
Alexander walked through the Great Hall alone one evening, inspecting floating candles, jack-o'-lanterns, and enchanted mist.
Satisfied, he folded his arms.
A bright smile spread across his face.
Halloween was ready.
And Hogwarts had no idea what was coming.