Logan had been under the Imperius Curse before. It was a horrible experience. You were completely removed of any and all control over the one thing that you should by rights be able to direct: your own body, your own actions. But the worst part about the curse was that you were still in possession of enough of your faculties to recognize the loss of control and to fight, sometimes vainly, against it. Logan had fought, and had through much practice trained himself to shut out the voice of the caster and ignore the commands given to him. He had been able to do this because of that belief, the belief that no one but he had the right to control his behavior.

The Dementor’s Kiss Curse was strangely peaceful, by comparison. It had been surreal at first. When Garrow had performed the spell on him, there had been a few moments of excruciating pain, like his heart was being ripped from his living chest; then he had been aware of himself, of his body, collapsing where he’d stood. He was aware that he laid there until he felt the urging of a strange and unfamiliar presence in his chest, pushing him to stand—and he had stood. Had he not felt that urging, he wouldn’t have moved, and likely would have remained there a very long time, probably forever. All his motivation to live, his will, was completely sucked out of him. His beliefs, his ideals, the forces that drove him—gone. All of them gone. There was no fighting it, no hope. No will of his own.

Now, he stood before a table covered with charts and notes in handwriting that he recognized as his, with that same strange presence—Garrow—urging him to finish. Finish what? There was a sharp pain in his chest and Logan’s hand came up listlessly to rub the place that had hurt. Oh. The spell, the spell the notes were about. Why finish it? It worked, a distant memory told him that it worked. He felt an overwhelming sense of imperfection and he glared at his notes, unaccountably frustrated with them. There was a problem with the spell. A problem that needed fixing. He recognized that he had the knowledge to fix the spell. What was the problem exactly?

He lifted his head lethargically and looked at a small, rune-engraved metal box winking maliciously at him from the mantle above the fireplace. He recognized, too, that something of his was in that box. He knew it was locked, but he was aware that he had the ability to open it…but why? Why even bother? For he remembered that the box was complicated, and he was very sure that he did not want complicated. Better just to avoid the thing. He looked away and tried again to remember what the problem with the spell was. He felt another pang in his chest.

“People see boxes and immediately think to open them," Garrow said irritably. "And if they open this box? Then the soul is just up and released, just like that! No. Storage must be more secure, less obvious. It must look less like a typical container.”

Yes; the problem was the storage of souls. That’s what Garrow wanted him to fix. Logan didn’t care about it. Given the choice, he felt he would not like to work on this. But Garrow’s obsession was a constant, throbbing pain in his chest, and Logan turned his thoughts apathetically to the perfection of the fourth unforgivable.