I have been waiting for a very long time to tell the truth, and to learn the truth. I have waited a lifetime. But the more of it I have experienced, the more fluid time becomes. It does not always progress in a strictly linear fashion. Sometimes it ebbs and flows, as in my own experience of ageing, and then growing younger again. Perhaps, then, I should not use 'lifetime' as a unit of measure.
Causality and order, too, are not quite so rigid as we are accustomed to think. For example: Probationary Constable Peter Grant met me for the first time when I walked up to him by the portico of the Actors' Church on a freezing winter night and said, "Hello. What are you up to?" However, I first met Detective Sergeant Peter Grant when he jogged up to my doorstep on a mild autumn afternoon and said, "There you are, sir. It is you, isn't it?"
Perhaps I should begin at the beginning. Unfortunately, I really have no idea just where that is.
Though I pretended ignorance, in truth I had some familiarity with the Harry Potter novels before I took Peter as an apprentice. Perhaps ten years earlier, when the imminent release of one of the middle books in the series caused a flurry of anticipation that occupied a significant fraction of the space and the sales clerks' attention in my favourite bookstore, I purchased and read the first two Harry Potter books. They were amusing enough but, of course, appallingly illogical. Two books were quite sufficient to understand the references that I had begun to overhear about "Muggles" and the "wizarding world." There was no need for me to waste time on more of them.
Partway through Peter's second year as my apprentice, I made my way up the iron stairs of the coach house to find him and Lesley on opposite ends of the couch with their legs tangled under a blanket in the middle. Lesley would occasionally leave her mask off in private, but she was wearing it now, perhaps to keep her face warm. The 'tech cave' did get rather chilly of an autumn evening.
Peter had muted the television as soon as I stepped in the door, and now looked at me expectantly. "Do we have a shout?"
I shook my head. "There will be some rugby on later. I thought you might show me how to find the right station."
"Of course, sir. Er. Thomas." He had not taken easily to the suggestion of using my Christian name during leisure time.
"There's plenty of time to finish watching your -" I glanced at the screen. "Oh. Harry Potter?"
"You rec'nise it?" Lesley said in surprise. Her speech was much better these days, but sometimes still slurred when she didn't prepare her words carefully.
"The actors and their costumes have been plastered in advertisements all over London for the past decade," I said. "So, which movie is this?"
"Er..." Peter did something which caused a few lines of information to appear at the top of the screen. Harry Potter and the Prisoner of Azkaban, it said.
"Third one," Lesley said more informatively.
"We can watch something else, if you'd rather," Peter offered.
"No, no, carry on." I started to pull the chair away from the computer desk.
"Plenty of room on the couch... Thomas," said Peter, shifting around.
I thought Lesley's eyes narrowed, but Peter would not be dissuaded, so I sat on the end, warm from his body, while he moved to the middle where he could press up against Lesley with the blanket over both their laps. The couch was large enough that there was no similar excuse for proximity between Peter and me. But it was comfortable nonetheless. Peter lifted a corner of the blanket and I shook my head.
We watched the movie, which appeared to be approaching its dramatic climax. The story was more complex than the two books I had read, and a number of things happened that were more unpleasant than I thought appropriate for children's entertainment even in this modern age. Eventually there came a point where the girl revealed that she possessed a time-travel device, and she and the eponymous Harry went back in time a few hours to fix some, but not all, of the unpleasantness. After that, the plot wrapped up in short order.
"Does that work?" said Lesley. "Time travel, I mean." Her mask was, as ever, expressionless.
Peter muted the sound of the credits and turned to hear my answer.
I cleared my throat uneasily. "There's nothing about it in the literature except for speculation. No reliably recorded cases, and for the highly questionable anecdotal examples, there is no suggestion of what mechanism might have been responsible."
"So we can't just ask the Ministry for a time-turner?" Peter's voice was falsely light.
"Nothing of the sort. But I suspect, if time travel did work, it would in fact be something along these lines." I waved a hand at the screen. "No... popping back to correct some mistake and changing everything in the process. Instead you would find that you cannot change what has already happened."
"But they did change it," Peter said. "Buckbeak didn't get executed."
Lesley made an impatient noise. "Everything they witnessed turned out just the same. They were just wrong about what they thought happened."
"So... you can't change what happened, but you can change how it happened?" Peter said slowly.
"Hmm, something like that." I leaned forward, staring blankly through the scrolling words on the screen.
Peter, ever curious and distractible, continued to muse. "Then it relies on the time traveller having incomplete knowledge of the situation?"
"They thought they knew, but their knowledge was based on hidden assumptions," I said slowly. "Witnesses do tend to do that."
Lesley was evidently beginning to enjoy the debate for itself, and not only because she wished she could travel back in time and fix her own life. "All right. Suppose they had actually seen Buckbeak's dead body the first time around. You're saying they wouldn't have been able to change that, then?"
"Unless..." Peter said, "they went even further back and, like, drugged Buckbeak or trained him to play dead on command, or something like that."
"That's ridiculous, Peter, he was meant to have his head chopped off. They're not going to fake that with a drug, are they?"
"The key is, don't try to change what happens, just change the context, is all I'm saying."
Lesley scoffed. "You would think magical time travel would be good for more than just staging a play."
I stood abruptly. "I should be going."
Peter started, turning back toward me. "What about your rugby?"
"Not really teams that I care about. Thank you both for... a pleasant evening."
"Anytime, sir." He got up to see me out.
As I started down the stairs I could hear Peter musing, "So why do you think Dumbledore told them not to let their past selves see them? What would have happened?" Their voices faded away as I reached the bottom of the steps.
I suspected Lesley would make sure they returned to opposite ends of the couch. But they were enjoying their movie and their discussion well enough, so there was no need for me to get in the way.
In any case, I had some thinking of my own to do.