It is customary for children to go to the nearest relative. Orphanages do not really exist anymore, and children go to foster care now instead.
In the 1800s, children who were abandoned by their parents or who lost their parents would go to orphanages. Even then, the idea of foster parents began to become common in the phenomenon of the Orphan Trains, which shipped orphans from the cities out west. Farmers or other people who wanted a child would take one in and eventually adopt one. Most institutional orphanages were discontinued in the twentieth century and replaced with the foster care system, where children live with families who take care of them. The families might be strangers or relatives.
When Maniac was orphaned, it was natural that he would have been sent to the closest living relatives. This is usually the first choice if a relative can be found. Relatives are usually vetted by the foster care system, to ensure that they are capable of raising a child. Despite the description, the relatives must have passed the test.
Aunt Dot and Uncle Dan hated each other, but because they were strict Catholics, they wouldn't get a divorce. Around the time Jeffrey arrived, they stopped talking to each other. Then they stopped sharing. (Ch. 1)
It seems like Maniac’s aunt and uncle were doing all right up until around the time he came. Sometimes a major life event is a stressor. It might actually be that having such a big change in their life, like taking in a young boy, might have brought out some things about themselves that they had to face. It caused so much stress that they began fighting. It is sad for Maniac, but it happens sometimes.
And that's when the running started. … Never again to return to the house of two toasters. Never again to return to school. (Ch. 1)
Poor Maniac was young, and this was more than he could take. He became stressed by the household. This is why he screamed during the recital, and ran away. The little boy, tough as he was, just did not want to deal with these adult problems.
It is probable that they tried to find him, but they couldn’t. Maniac was very smart, and a clever boy like Maniac would know how to avoid being found for some time. Also, the aunt and uncle might not have wanted to admit their failure. Did they look for him? Did they miss him? We can only hope. However, they may have just been relieved that he was gone.
Unfortunately, children do disappear from the foster care system every day. Sometimes the foster parents, whether they are relatives or not, are not acting responsibly. They may want to continue collecting money for the child and not to report the child missing. Sometimes they do report the child missing, but the foster care system does not have the resources to find the child. One more missing foster child will not make the news, so no one is looking.