The first match

"Soul Splitting?"

Gavin sat at the desk in the Room of Requirement, a dragon hide notebook spread open before him. His quill had dotted the page with ink several times without writing a single word.

He was sorting through the information he had obtained from the Tom in the Diadem.

In the final instant before the Obscurus devoured that soul fragment, he had used the black mist as cover to cast an extremely faint bit of Legilimency.

The same sort he used when playing rock-paper-scissors with Cordelia.

Legilimency at that level yielded very little information, but Gavin had not dared to use any more than that.

He had wanted to salvage something useful before Tom disappeared.

He had admittedly been a little reckless. If Dumbledore had noticed, his memories would probably have been sealed already.

He admitted he had taken a gamble.

He had gambled on Dumbledore having only just learned to enter the consciousness space and not yet understanding the form of primordial magic.

Fortunately, he had succeeded.

And Dumbledore seemed entirely unaware of it.

His original goal had been quite clear: the method and principles behind making Horcruxes.

If he could break down the mechanism by which Horcruxes absorbed life force and apply it to the Obscurus's consumption problem, using the Obscurus without limits would no longer be a dream.

He had even specifically asked Dumbledore what life force actually was.

Dumbledore had thought for a long time before finally answering, "I can sense its existence, but I can't explain what it is."

An old wizard who had lived for a hundred and ten years and mastered alchemy and magic understood life force about as well as Muggles understood dark matter—

He knew it existed, but not what it was.

So Gavin could only rely on himself.

The