This will be added to as I think of things.
- Remy and Emile were from the same litter, actually, but Remy was about a minute or two before Emile. Thus, IMO, Emile is the little brother by a few minutes, and the fact that he's twice Remy's size is the irony of life and the fact that unlike Remy, he will eat anything. Picky rat means tiny rat.
- The reason Remy and Emile are so close is because when they were both tiny, they both stood up for one another in play fights. When they got bigger (and Emile got a lot bigger) they tended to stick together whenever the fights stopped being play fights. Between Remy's speed and Emile's size, after one or two scuffles nobody really bothered them anymore.
- The reason this continued after Emile was no longer tiny is because their father Django pulled Emile aside and asked him to keep an eye on Remy and keep him out of trouble, since Emile could protect him. Emile didn't correct his dad and has never told Remy about it.
- I like to think that Remy's mother was formerly a pet rat. Thus, she probably humored and probably sparked Remy's fascination with the human world. (Hey, Django had nothing to do with that one.)
- However Remy's mother died, it probably wasn't directly by a human hand because I can't see Remy being as curious about humans otherwise and Django would have hated them even more.
- Remy's mother was also probably the peacekeeper of the family, but ever since she died, Emile took up that role.
- Even before Remy discovered the phenomenon of cooking, he and Emile were always running around having adventures they weren't supposed to. While Remy probably dragged Emile into most of them, Emile was the one who came up with the dare of seeing if they really could enter the old lady's house through the toilet.
- Emile isn't just good at hiding things, he has a tendency to hoard them. Not just food, either. Shiny things, trinkets, nothing humans would miss but always something that caught Emile's eye. When Remy found out about it, he didn't say a word to Django. But whenever he wanted to stash something, Emile was the first rat he'd seek out.
- Remy actually learned to use a typewriter once using paws and tail when charades just were not enough to communicate to Linguini what he wanted to say.
- While they were separated in Paris, Emile missed the adventures he'd had with his brother. He might have whined a lot whenever Remy talked him into the crazy idea of the day, but secretly he kind of liked the adventures they had and kind of relied on Remy to come up with them. (But not getting struck by lightning. Noooo.)
- When they first opened La Ratatouille and Remy read over the regulations that explain why rats in kitchens are such a health violation, he took to spending an hour cleaning up prior to starting work in the kitchen for the day, not just paw washing.
- Remy and Linguini tried to see if they could get a hairnet of sorts to work for Remy, but after Linguini had to try to cut him out of it before he suffocated and Colette had to step in before Linguini trimmed off an ear or some of Remy's tail, they abandoned that idea. Colette just checked every dish extensively for fur after that, but amazingly neither she nor any of the patrons have ever found hair in their food.
- Colette was the one who found the tiny toque Remy wore at the end of the movie. It was purchased partly as a joke, but Remy was delighted and it actually made it easier to reconcile the idea of a rat as a chef.
- Remy ate a lot better when he started living with Linguini since he didn't have to pick through garbage for something edible anymore. He didn't get much bigger, though, because all the acrobatics involved in puppetering and cooking pretty much was a workout and a half.
- While Remy always wanted to be a cook, Emile kinda-sorta wanted to play music. Django took no note of this because a) Emile was nowhere near as passionate about it as Remy and b) there are such things as rat musicians already in their world.
- I still haven't decided what the rest of Gusteau's staff did post-movie. I'm pretty sure none of them ever told a soul about Remy because... well, for one thing, no one would believe it and it would be embarrasing. Also, denying it made Skinner look even more like a nutjob when he tried to tell people about it, and NOBODY at Gusteau's liked Skinner at all. They might have thought Linguini was crazy, but he wasn't an ass.
- Sadly, I suspect Horst is not working at La Ratatouille at the end of the film. Colette is sous-chef there, period, and I don't think they'd be comfortable with the role reversal. I haven't decided about the rest of the old guard, although with Linguini as the maitre'd I'm betting Mustafa didn't come with them either.
- Oh, and I don't think the health inspector ever mentioned seeing the rats cooking - he's still in denial about that part of it, and suspects that Skinner planted them as revenge. Not that it stopped Gusteau's from getting shut down, but the rumors that Skinner had set the whole thing up still got around and allowed the staff to get jobs elsewhere.