In the past, Rowan Mercer would never have casually taught magic he'd learned in other worlds to anyone else.
Power, once shared, had a habit of circling back in unpleasant ways. If an enemy learned his spells and turned them against him, that would be an unforgivable mistake. But things were different now. His strength had grown enough that, as long as he avoided teaching his core techniques, the spread of a few auxiliary spells posed no real threat.
The Mirror World spell was a perfect example. It carried no offensive power, and even if an enemy used it, Rowan would sense it immediately. In Middle-earth, when he founded the so-called Middle-earth Hogwarts, he planned to teach Light magic and Giant magic to the elves. Both were constructive disciplines, unlikely to draw the displeasure of higher powers. Teaching killing curses, on the other hand, would be a fast way to lose divine goodwill, even if Morgoth himself were defeated.
He had done something similar in the Fairy Tail world. Rowan had compiled and translated several spells from the wizarding world into grimoires and placed them in the Fairy Tail guild library, including the Repair Charm the guild needed most. Because the two worlds' magical systems differed fundamentally, he had rewritten the spell to fit their framework. It was harder to learn than native magic, but not impossible.
And yet, no one had bothered.
Fairy Tail mages believed their own magic was the best match for them. Even Makarov, who valued the Repair Charm most, refused to learn it, reasoning that as long as Rowan existed, there was no rush. Someone like him would always pass the knowledge on.
That memory surfaced as Rowan accepted the Marauder's Map from Fred and George Weasley.
"Deal," the twins said without hesitation.
To them, the map's usefulness had already peaked. They knew every secret passage in Hogwarts, and its main value now was avoiding Filch. Compared to that, learning the Mirror World spell was far superior. The map only worked inside Hogwarts. The spell worked anywhere and elevated their pranks to an entirely new level.
Rowan pocketed the map.
"Good. I'll prepare proper notes for you tomorrow. If you don't understand something, come find me."
Different worlds required different translations. Harry Potter magic and the Apprentice Mage world aligned fairly well, but Fairy Tail magic had required far more adaptation. Fortunately, teaching the twins wouldn't be difficult.
Back in the Slytherin dormitory, Rowan finally slept.
Over the next few days, his schedule settled into a rhythm. He studied Portkey creation under Dumbledore's guidance, taught the twins the fundamentals of the Mirror World spell, and dissected the Marauder's Map layer by layer.
October sixteenth.
Hagrid's hut.
"Rowan, thanks again," Hagrid said, setting down a plate of rock-hard biscuits. "If you hadn't stepped in, Buckbeak would've been done for."
Rowan took a bite, chewing with effort.
"It was Malfoy's fault to begin with. No big deal."
During the first Care of Magical Creatures class of the year, Draco Malfoy had insulted Buckbeak and been injured as a result. He'd threatened to involve his father and have both Hagrid fired and Buckbeak executed. Rowan had intervened, persuading Malfoy to drop the matter.
Lucius Malfoy's influence at the Ministry was no joke. Even Dumbledore would have struggled to stop the execution if things escalated.
Hagrid sighed, clearly still shaken, then brightened when Rowan changed the subject.
"Hagrid," Rowan asked casually, "you like dragons. Do you know where they're usually found?"
Hagrid's eyes lit up instantly.
"Oh, absolutely. I raised one once, remember? I've read everything there is."
He rattled off locations with enthusiasm: Australian Opaleyes in New Zealand and Australia, Welsh Greens and Hebridean Blacks in Britain, Hungarian Horntails now mostly in Romania. One by one, he listed every known dragon species in the wizarding world.
Rowan listened carefully.
Over the next few weekends, he planned to hunt one of each.
Not for glory.
For integration.
This was his Dragon Crystal Integration Plan.