I think there may be a misunderstanding as the term 'charters' doesn't seem to have an obvious meaning in relation to this story. Maybe it was a typo? If we consider the characters instead, they are significant as they drive the plot. For instance, Craig's relationships with his friends and family change throughout the story as he grows.
One 'kinda scary story' could be about a haunted house. There's a old, dilapidated mansion on the outskirts of town. People say that at midnight, strange noises come from it, like the creaking of floorboards and the moaning of a long - lost soul. Lights flicker in the empty rooms, and if you look closely, you might see a shadowy figure in the window.
Well, if by 'charters' you mean some sort of official documents or agreements within the context of 'It's Kinda a Funny Story', there are none that I recall. The story mainly focuses on the personal growth of the main character, Craig. It's about his experiences in the hospital and how he interacts with the other patients and staff.
I'm sorry I can't directly create a Venn diagram here. But generally, for this story, you could have one circle for the main character's experiences at home, another for his experiences at the hospital (if that's a major setting in the story), and the overlapping part could be things like his personal growth that occur in both environments.