The neighborhood surrounding the Professor's store was made up of inexpensive apartment houses, little family-owned shops, and small, aging homes. The people of the area, many of whom had some connection with the university, could trace their ancestors to every continent, and just about every country in the world. (1.4)
Because Melanie, April, and all the other kids live in a college town, they are a part of a close-knit and diverse community. The entire neighborhood communicates with each other and helps to watch out for the kids. Plus, that rainbow of people all getting along could tell a lot of places in the world a thing or two about understanding in spite of difference.
Melanie was eleven years old and she had lived in the Casa Rosada since she was only seven. During that time, she'd welcomed a lot of new people to the apartment house. Apartment dwellers, particularly near a university, are apt to come and go. Melanie always looked forward to meeting new tenants, and today was going to be especially interesting. (3.1)
Melanie has lived in the Casa Rosada for so long that she's kind of an ambassador for new tenants—especially the kids. She thinks of it as her role to say hello and introduce kids to the neighborhood—and hopefully to become their friend, too.
But it was when Toby and Ken gave her a nickname that Melanie knew for sure that the worst was over. Toby Alvillar and Ken Kamata were two of the biggest wheels in class, and if you were really hopeless they simply didn't notice you—it was as if you didn't exist. (6.7)
When Toby and Ken give April a nickname, it's clear that she's now one of "them." She's a part of the school and neighborhood community, and the other kids accept her completely, even if she is a bit different.
The next morning April and Melanie went dutifully down the little dark basement hallway and knocked on the door of the Chungs' apartment. Almost immediately, the door across the hall opened and Mr. Bodler, the janitor, looked out. "Oh, hello there, young ladies," he said. "Thought I heard someone knocking on my door." "Hello, Mr. Bodler," Melanie said. "We've come to get the new girl and take her to school with us." (7.18-19)
Now that April is Melanie's best friend, they can share welcoming duties when a new kid moves into the building. That's exactly what they do when Elizabeth Chung moves in, and it's a good thing too, since she turns out to be a great addition to the Egypt Game.
Twice a day a few children could be seen walking to and from school, but they went quickly and in larger groups than usual; and many other parents arranged car pools, even for children who only had a few blocks to walk. Afternoons and weekends, which usually rang with a medley of shouts and laughter and pounding feet, dragged by in a strange, uneasy silence broken only by the dull hum of traffic. (8.13)
After the murder happens, the entire neighborhood goes into lock-down and the kids are carefully watched over. The community is definitely terrified that something bad could happen to another child.
It wasn't only the boys and girls of Orchard Avenue who talked and talked. The grown-ups did, too. Everybody had theories and opinions, and everybody had heard rumors they were eager to repeat. There was one rumor that was particularly persistent and particularly troublesome to the members of the Egypt Game. It had to do with the Professor. (8.21)
The murder is the biggest news in the community, especially because it remains unsolved. However, having a close-knit community also means that gossip spreads like wildfire—including the rumor that the poor Professor could be a suspect.
The trick-or-treat group was a milling mob of devils, witches, tramps and monsters. Mr. Barkley, who always acted as if being the father of six-year-old twin boys was almost more than he could stand, looked positively exhausted; and even Mr. Kamata's sturdy real-estate-salesman's smile was beginning to wilt. (10.1)
The dads are just trying to help out the community and their kids, but that doesn't make chaperoning a huge group of kids easy. It's clear that they at least kind of regret their decision as the night wears on.
"...But a lot of them are neighborhood people who are feeling ashamed about suspecting him when he was innocent. They come in here and buy things they don't even need, just to ease their consciences." (22.14)
Looks like it's not just rallying around for the sake of rallying around. A bunch of the neighborhood folks are coming in to buy things at the Professor's store because they feel guilty about suspecting him of the murder. They're making amends with their wallets. Well, it's still good for the community.
There were two or three browsers just looking around; and the Professor was wrapping something up for a customer; and over by the window Elizabeth's mother, Mrs. Chung, was dusting some figurines and arranging them in the display case. The whole situation looked different—cleaner and brighter and not so cluttered. (22.6)
The kids are totally shocked when they enter the Professor's store after the murderer has been caught—and find that the store is full of shoppers. It looks like the community has decided that he's not so scary after all, and they're rallying around him because of his role in catching the killer.
At a P.T.A. meeting at Wilson School, a couple of really red-blooded mothers stood up and volunteered their husbands to take large groups of trick-or-treaters around the neighborhood. Before long some other fathers got shamed or nagged into doing the same thing, and by the day before Halloween nearly all the kids at Wilson were signed up to go around trick-or-treating with some large, chaperoned group. (9.2)
The community also rallies together when it looks like Halloween will be ruined. By volunteering to chaperone large groups of trick-or-treaters, these parents prevent the possibility of kids rioting about having Halloween cancelled, but also make sure the kids stay safe.