A full two hours passed before Tom finished combing through every inch of the Marauder's Map. By then, he had a basic grasp of how the Marauders had built it.
The map's greatest strength lay in marking names and tracing movement. Tom did not recognize the spellwork involved, so he called Grindelwald out to consult.
"This is an advanced tracery charm for living beings," Grindelwald said. "It marks and follows a target creature. It should be the work of the Potter family. They are very good at running."
Tom could not help nodding. The Potters were indeed excellent at flight.
According to legend, the Potters' forebears were the Peverells. The third brother escaped Death's hunt, and James Potter once slipped Voldemort's clutches three times.
"As for the way names show up..." Grindelwald pinched his chin. "True name magic. A fine thing. Tom, try to reverse engineer it. You could extend it into many uses."
"Such as making others too wary to speak my name?" Tom asked with a smile.
Andros, listening to them, could not resist. "Tom, you sound more and more like Voldemort. Why should a perfectly good name be unsayable?"
"Only a joke," Tom shrugged. "I want to hide my true name so no one can curse me with it later."
It sounded similar to Voldemort changing his name, but what Tom described was more abstract, not altering the string Tom Riddle, but stripping away the part that represented his true name's essence. It was a pain to explain, and even messier to perform.
For now, Tom had merely warded his name with standard protections, far less secure than the thing he envisioned.
These pure-bloods... they carried treasure in their pockets.
True name magic was, in all likelihood, a Black family heirloom. Lupin and Peter Pettigrew might have helped with the map, but they were mostly gophers. The real core had been Sirius and James, two scions steeped in family lore.
Madam Greengrass had helped Tom collect many pure-blood curiosities, but no one would hand over a core secret like that.
Owing a favor did not mean one would sell the family crown.
Even so, the map gave Tom a rush of inspiration. He had been moving forward so smoothly that he had nearly forgotten how many treasures lay within reach. He would have to do a proper sweep when the chance arose.
"Tom! Tom! It is the holidays, stop working so hard and come out to play!"
Daphne's cheerful shouting floated up from downstairs. Tom smiled helplessly, put the map away, and went down to keep the little witch company.
...
At lunch, the house elf Parra had laid out a glorious spread. Daphne reached for extra cannoli, but the silver platter reflected a face a touch rounder than before. Her expression crumpled. With a pained little gasp, she set the sweets aside.
Tom almost burst out laughing. He decided there was no point hiding it anymore.
"Daphne, from today, eat as you please. I promise that whatever weight you want to maintain, you will maintain."
Swish, swish, swish.
All three girls looked at him. Daphne's golden hair seemed to float as she practically flew to his side. "Tom, the slimming potion... you finished it?"
"I did. I even had someone test it, and the results are accurate."
Tom took out the potion he had prepared long ago. He had planned to give it to Daphne as a birthday present, only a month or so away. Seeing her eyes now, he sighed. Time to find another gift.
"Jelly?"
Hermione and Astoria leaned in, peering at the bottle's contents. Unlike common draughts, it was set like a gel.
"Yes, it tastes rather like jelly. I call it the Path of the Heretic Slimming Elixir."
"The Path of the Heretic?"
All three girls spoke at once, baffled by the strange name.
"Right." Under their puzzled stares, Tom explained, "Its main purpose is not slimming. It is a temporary boost to magical power. It lets your spells hit much harder."
"Ah?" Daphne could not hide her disappointment. "But you said it was a slimming potion."
"I was not finished." Tom caught her hand, motioning her to be patient. "I use the side effect to slim down.
"In Dark magic, there is a class of sacrificial magic that burns flesh to boost magic for a short time. Voldemort knows it and taught it to some Death Eaters."
For example, Peter Pettigrew.
Tom added silently, recalling the day a single sacrificed finger blew up half a street. By that yardstick the little rat was not exactly weak, merely vicious and self-serving.
Hermione and the others had turned pale, staring in horror at the pretty crimson jelly.
Daphne swallowed. "Tom, I do want to lose weight, but... not that badly, surely?"
"Relax. I optimized it. The flesh converts straight to energy, and there is a numbing component so you will not feel pain. One bottle consumes about one kilogram of body mass. After you take it, you will feel full and swollen. Spend the excess magic and your body returns to normal."
Tom's reputation was solid with Daphne. Doubt vanished from her eyes. She hugged the bottle. "Then I will eat first and test it after."
Hermione hesitated, then lifted her hand. "Tom, do you have more? I want to try it as well."
Which girl does not yearn to eat without gaining weight? Hermione could not resist either, though she was not as single-mindedly snack-happy as Daphne.
Lunch vanished in no time. Daphne let go completely, eating twice, maybe thrice, her usual amount. A tiny belly appeared when she finished. She dragged Tom upstairs to weigh in, then rushed to the back garden to test.
She downed the potion like jelly. Heat rose under her skin, no pain at all, only a restless tide of energy with nowhere to go.
Tom conjured several targets before her. "You can begin."
"Stupefy!"
"Diffindo!"
"Bombarda!"