After briefly considering Shawn's "explanation," Dumbledore chuckled.
"It's good that you think that way. And I can see that your understanding of magic, especially of the soul, has grown deeper.
"This modified Petrification Charm no longer petrifies only the body. It even petrifies the soul's outer layer.
"If you ever manage to petrify a soul completely, it could almost rival the death gaze of a fantastic beast like the basilisk.
"Hmm? That would qualify as dark magic, I suppose. You'll need to use it with caution."
Shawn inwardly marveled at the Old Beekeeper's sharp eye. A single glance had been enough for him to work out nearly everything.
But he certainly wasn't going to admit that he specialized in dark magic, so he continued spouting nonsense.
"Headmaster, I've mainly been researching this spell because I've been trying to find treatments for the Longbottoms and Astoria lately.
"The Longbottoms' souls have been tortured into tangled messes. Touch one strand, and the whole thing shifts. The blood curse, meanwhile, involves a curse entwined with the soul.
"That's why I've been developing a spell that can petrify souls. If it works as intended, it would be like administering an anesthetic in Muggle medicine, temporarily preventing patients from instinctively resisting.
"Wouldn't that let me piece their souls back together and remove the curses within them without causing any harm?"
Shawn had originally thrown out a random excuse to allay Dumbledore's suspicions.
But the more he said, the more naturally the words came, and the more feasible the idea seemed.
He hadn't expected the modified Petrificus Totalus, which he had previously paid little attention to, to have a use as an "anesthetic."
With his vast knowledge, Dumbledore also fell into thought after hearing this, finding the proposed approach highly constructive.
A glimmer of hope flashed