Over the years there's been an endless series of guesses about who fixed Little Chicago, but there usually hasn't been much to separate any one theory from the legion and assign more credibility to it than many of the others. The questions to be answered are: how would someone get into Harry's home to fix the model without leaving any trace of their passage; how would someone even know that Little Chicago existed, or how to repair it; and why would someone enter Harry's home without his knowledge, fix the model, and then leave without ever letting him know? I think I know the answer to the first two questions, though the third is still mostly a mystery.
In
Changes, Lea told Harry this:
"Ensuring the well-being of my spiritual self," I murmured. Then I blinked. "The garden, the one on the other side of this place... It's yours."
"Indeed, child," she said. "Did you not think it strange that in your turmoil-strewn time here none of your foes-- not one-- ever sought to enter from the other side? Never sent a spirit given form directly into your bed, your shower, your refrigerator? Never poured a basket of asps into your closet so that they sought refuge in your shoes, your boots, the pockets of your clothing?" She shook her head. "Sweet, sweet child. Had you walked much farther, you would have seen the mound of bones of all the things that have attempted to reach you, and which I have destroyed."
"Yeah, well. I nearly wound up there myself."
"La," she said, smiling. "My guardians were created to attack any intruder-- including one that looked like you. We couldn't have some clever shapeshifter slipping by, now, could we?" She sighed. "You took a terrible toll on my primroses. Honestly, child, there are elements other than fire, you know. You really ought to diversify. Now I have two gaping maws to feed instead of one."
"I'll... be more careful next time," I said.
"I should appreciate such a thing." She studied me quietly. "It has been true for your entire lifetime, child. I have followed you in the spirit world. Created guardians and defenses 'pon the other side to ward your sleep, to stand sentinel over your home. And you still have only the beginnings of an idea of how many have tried." She smiled, showing her delicately pointed canine teeth again. "Tried, and failed."
Which also explained how she was always near at hand whenever I had entered the Nevernever. How she would be upon my trail in seconds whenever I went in.
Because she had been there, protecting me.
We don't know when Lea went into the ice at Arctis Tor, or when she came out, but we do know that she was there during the period of time between Harry's conversation with Mab in
Dead Beat and the time he came to Arctis Tor in
Proven Guilty. This means that for the nine months between those two events, it wasn't Lea who was watching over Harry, but Mab.
Lea's garden connected directly to Harry's lab. Mab, being Mab, seems like she would certainly be capable of looking through the veil between Earth and the Nevernever so that she could see what was on the other side, if she chose to. Mab already had an interest in Harry as her next Winter Knight, and Lea's responsibilities toward Harry would've given her an additional motive to keep an eye on him. She could have scried on Harry many times prior to
Proven Guilty, watching him as he put together Little Chicago. And, being Mab, she could've seen what Bob did not: that Little Chicago was flawed, and if Harry used it before it was repaired, it would fry his little wizard brain.
So, one day, on the day PG begins, Harry gets a note from the Gatekeeper about black magic in Chicago, and he decides to try using Little Chicago for the first time. Mab learns of this in whatever way she learns things-- though in this case, the Gatekeeper may have sent her a note telling her about it-- and realizes that if something isn't done, her future Winter Knight is very shortly going to die of his own stupidity.
I don't know why Mab didn't simply step into Harry's lab while Bob was there, but from the clandestine way that LC was fixed, we can guess that she didn't want Bob to see her doing it. Or maybe she didn't want
anyone to observe her fixing it; the brownies aren't allowed down there, so there may not have been any observers around at all. Or maybe, if she and Bob were in the same place at the same time, she would be compelled to take some action against him, and she didn't want to do that yet because he was so useful to Harry. Just a guess.
Anyway, whatever her reasons were, Mab apparently didn't want to fix Little Chicago with an audience watching her. So she needed to find another way to prevent Harry from using the model before it was corrected. And while we don't know for certain that Arctis Tor had already been sacked by this point, it's quite possible that it had been, so Mab may also have had motive to interfere with the Black Council's plans. Mab uses her vast knowledge and foresight to plot out likely events, and realizes that if she sends fetches to plague Molly's life, Molly may contact Harry in time to head him off from getting his brain fried.
Mab may also have sent the drive-by car rammer to slow Harry down on his way home at the beginning of PG. That's not really vital to this theory, but without that incident Harry probably would have made it home in time to use Little Chicago before Molly could contact him. So maybe that can be laid at Mab's feet, also.
Harry gets bumped off the road and side-tracked. Mab sends fetches to screw up boyfriend Nelson's life. Nelson is arrested. Molly calls Harry for help, interrupting him before he can use Little Chicago. Harry goes to see her and finds himself coincidentally already onto the case of black magic, without ever needing to use LC to track it down. He eventually goes back home and grabs Bob, which leaves the lab empty of observers. Mab takes this opportunity to pop over, fix Little Chicago, and leave.
And that's the end of the relevant parts of the theory. I don't know why Mab had the fetches grab Molly and take her to Arctis Tor. I suspect she was killing a few birds with one stone, though I can only guess what the birds might have been. A lot more speculation about that can be found in
knnn's recent thread,
over here.
Everything we needed to know in order to make this guess was actually in
Proven Guilty, except for the vital information that Lea's demesne was across from Harry's laboratory. That gave Mab a simple means of crossing directly into his home, and her mandatory protection of him gave her a reason to be watching him. That, in turn, gave her plenty of opportunity to find out about Little Chicago.
If this theory has already been laid out like this by someone else, I truly apologize. It's not my intention to try to take credit for something that someone else may have gotten to first. The threads and posts theorizing about Little Chicago could probably fill a small library, and if it was posted here somewhere, I missed it.
Anyway-- this is what I think happened with Little Chicago. I think it makes more sense and is more believable than any of the other possibilities I've heard of, including the various time travel ideas. (I've never liked the time travel theories much. It always seemed too simple, while at the same time taking a major risk of paradox.)
