My Foster's Home Theory:
Why does Mac have an Imaginary friend in the first place? Why does his bother bully him? His mother is never around. Where is his mother? Where and who is his father? The lady you think is his mother at the beginning of the show...who could she be? Where does the rest of those imaginary friends come from?
There is one theory that Its all in Frankie's mind and that she has autism...living in her own world. I think It's opposite.
Mac is actually an orphan. His mother was never around, that's why the imaginary friend, Bloo was needed, to keep him company. His biological mother protected Mac the most because he was too young to defend himself. The reason why his biological mother isn't around and his Father was never mentioned in the show is because his mother murdered the father for torturing her two boys and was charged with Voluntary manslaughter and sentenced to life in prison. The reason for Terrance's constant bullying is that he felt that their mom didn't love him. Seeing that she protected Mac the most, this created an anger toward his brother. Terrance plays into Mac's imaginary friend story only to make him suffer even more as he tries to separate them. Telling the lady that raised them (preferably a social worker they call mommy) Soon after going along with the story for so long, He too begins to believe in imaginary friends. Obviously sustaining some sort of brain disorder due to the beatings he got from his father, Terrence is not really bright but is bent on making Mac's life miserable.
As all hurt and tormented humans do, they find or create a place where they can no longer be bothered. Mac runs away from home after he is told by his "mother" the social worker, that he has to get rid of Bloo and to grow up. Terrance has told her that he was jealous of Mac. Terrance didn't have an imaginary friend and didn't comprehend how talking to air made the boy happy. So to balance things out the social worker "Mom" broke the news to Mac to stop talking to his friend. It was simply time to grow up. He runs away from home to another home of a grandmother and her granddaughter who takes him in. They kept him fed, sheltered and entertains his need of the imaginary friend. Soon he creates more friends because he feels the house is too empty. Each friend symbolizes his random fears, hopes, dreams, and truths about his life.
Bloo: Being the combined and "tamed" traits of his bio-father. Bloo is sometimes self-centered, egotistic, and narcissistic, a show off and has a knack for getting into trouble. The "trouble" here were with drug dealers and the police. Deep down Mac wanted to be friends with his dad but never understood why his father would want to hurt him. this left him sad and depressed. (blue)
Wilt: Was everything he remember his mom to be. Wilt is known for being excessively polite and apologetic, saying "I'm sorry" in almost every sentence. The stubby arm and stitches indicates that he had witnessed his moms beatings. Making Wilt tall only symbolized that he was too small or too weak do anything to help his mom. The color red also symbolized the love she had for him. A warm color indeed for the many times she had to hold him keeping him away from his father.
Coco: Coco was the excessive want to leave and the promised made by his bio-mother. He was once told they would take a plane to get away from his father. But the man found out and made it impossible them to leave. hence the reason coco is made up to be half plane. He never tried the drink Coco before...that was one of the beverages she promised constantly to let him try hence why Coco...only says coco.
Eduardo: the combination of how Mac would act around his father his father's potty mouth and the monster his mom had become when she finally killed the man. Eduardo's large size, overwhelming strength, and menacing demeanor shows that his mom had the upper hand. Maybe having the element of surprise. Eduardo is also docile, timid, lacks confidence, and is very compassionate. More of his mother's traits. Eduardo likes potatoes which were the only things Mac's mother would eat most of the time.
Mr. Herriman: He was the first to be created seeing how Mac needed some sort of order and father in his life when it came to all his problems. He also wanted an adult figure around as well. When Frankie had to go and to complete some errands. that would leave him alone in the house. Not counting the Madame foster for she acted as much as a child as he did and with Her mind slowly going as well, she wasn't very suitable to be a care taker for too long. Foster was not stable enough or sane enough at times.
Whenever Terrance came to visit, Frankie would allow it. And leave him to babysit. As Frankie didn't really care much of what went on in the house. She would always put on a nice facade to the boy and let him do what he wanted. As long as she kept her bedroom door locked, Frankie would be happy. Once returning she would kick Terrance out to return back home. Terrance never tells his "mom" where Mac is hiding and steadily plays coy with the police. To him...its a fun little game.
Frankie on the other hand is waiting for foster to pass on so she can inherit her fortune and needs an accident to happen.
The house itself was a fun park to Mac because it was old and had many path ways, escape holes, and many stairs. Of course his mind would expand on that creating a larger home for his imaginary friends.
After a few months. Frankie was going to be doing a lot more. Going back to school and such. so she needed someone to help "look after" poor Mac and her grandmother. Several people looking to "adopt" an imaginary friend, were her own friends trying to help out. But being as busy as they were they wouldn't stay long. It was merely to check up on him, say hi and go there merry way. Those visits soon beaome too friendly. Plenty of things became involved. drug abuse and rape was masked with happiness, "candy" and "games"
Frankie's friends were as twisted as she was and simply waited for that moment to happen.
Mac and Terrance's social worker has been looking for little Mac. Which is why she is never brought up again in the story...she never found him. So he stayed there in that house with a busy real friend, Frankie and her senile grandmother Ms. Foster.
Next in line to be Creepypasta-ed? Codename Kids Next Door!