How does Charles Wallace's relationship with Meg change throughout the novel?

When the
novel opens, Charles Wallace is Meg's caretaker. He seems to always be one step ahead of her and
his mother. This is shown early in the book, when he knows that both Meg and his mother will be
woken up by the storm and come down to the kitchen for a snack in the middle of the night. He is
waiting for them. He also meets Mrs. Whatsit, Mrs. Who, and Mrs. Which before Meg does. He is an
unusually intelligent and wise six-year-old who has insights that Meg doesn't.

When they get to Camazotz, however, their roles reverse. IT takes over Charles
Wallace's mind, taking advantage of a streak of arrogance in his personality, so...