There were dozens of children in the neighborhood; boys and girls of every size and style and color, some of whom could speak more than one language when they wanted to. But in their schools and on the streets they all seemed to speak the same language and to have a number of things in common. (1.5)
That's a poster for harmonious diversity right there. But as far as the heroes go, the nice thing about the neighborhood where they live is that it's full of children—which means that there are plenty of potential playmates when they go outside to play.
"Do you really still play with paper dolls?" April asked in just the tone of voice that Melanie had feared she would use. Not just because she was April, either. It was the tone of voice that nearly anyone would use about a sixth-grade girl who still played with ordinary paper dolls. (3.40)
April is only eleven years old, but she can still act superior when she sees Melanie doing something she sees as babyish. But when Melanie shows her the game, April is completely sucked in and has to admit that playing with paper dolls can be fun. That's the power of imagination.
"That's the way with Marshall," she said. "He's been awfully grown-up ever since—oh, since about the time he started walking. That is, about everything except Security. I guess he's not very grown-up about that. Dad says the reason Marshall needs Security is that he had such a hard time being a baby. Dad said being a baby offended Marshall's dignity." (6.19)
Marshall is only four years old, but that doesn't mean that he acts like a baby. At least, aside from his habit of carrying around Security the stuffed octopus. But aside from that one quirk, he's very mature for his age.
"How old is she?" she asked, letting her eyes go narrow. "I think her mother said she was nine," Caroline said. "Nine," said April, with a cool smile, "is a lot younger than eleven." (7.4-6)
April is very skeptical about Elizabeth Chung because she's only nine years old. Two years younger seems like a lot when it's the switch from single digits to doubles. How are they going to have anything in common?
But, since he wasn't even in kindergarten yet, he wasn't exactly fluent in either one. So towards the end of the hieroglyphic period, when he'd learned about as much Egyptian writing as he felt ready for, he hadn't had very much to do. (14.21)
It's not that Marshall isn't willing to learn the hieroglyphic system that the other kids come up with. It's just that he's not all that interested in reading and writing yet. Being mature for his age can only go so far.
Without exactly saying so, he managed to spread the rumor that he and Ken had an after-school job—a very serious job involving actual work. Toby figured that there was nothing less interesting to most of the kids he knew than an after-school job, and he was right. (14.19)
Toby and Ken understand the kid state of mind, which is how they're able to make excuses for not playing with the other boys after school anymore. They just tell them that they have a job. Which is about the most boring topic in the world to the other kids. Nice reverse psychology, dudes.
That day Marshall wouldn't even take part in the ceremony. He just sat on a box against the fence and watched with big sad eyes. Everybody tried to talk to him and cheer him up, but he wouldn't answer. Looking at him, the others remembered with a feeling of shock that he was awfully little. He usually seemed bigger. (18.11)
Poor Marshall. Sometimes the older kids forget that he's only four years old, but his maturity is put to the test when he loses Security and suddenly starts looking like a baby again. He's obviously heartbroken, and they don't know what to do in order to make him feel better.
Mom and Dad would never let them go alone, and if Dad went with them, the other Egyptians would never forgive them for giving away Egypt to a grown-up. Melanie had known that Marshall understood the importance of what she was saying and that he was trying awfully hard to believe that it was all more important than finding Security. (18.4)
Melanie feels awful about poor Security sitting all by his eight-legged self in Egypt, but she knows they can't explain all this to their parents. Adults just wouldn't get the whole Egypt Game thing. Plus, they'd probably get in trouble for sneaking out on Halloween.
"You know what? I'll bet you didn't leave Security in Egypt at all. Now that I think about it, I don't remember seeing him there today. I'll bet you left him at nursery school. I'll bet he's safe and sound in the playroom at nursery school, and you can get him in the morning when you get to school." (18.7)
Being the grown-up in the situation sometimes means padding the truth. Melanie doesn't actually believe that Security is at nursing school, but she says so in order to comfort Marshall anyway.
After that he started leaving Security home sometimes when he went places, and before too long he didn't need to have Security with him at all anymore, excepting to hold on to at night when he was sleepy. (21.51)
After the confidence-boost of catching a murderer, Marshall is growing up, which means shedding his old babyish habits. He's even willing to leave Security at home sometimes—which is a huge step for him. It looks like Marshall can take care of himself without having to have a stuffed animal around anymore. Let's just hope Security can get by on his own, too.