Character Analysis
Anne simply adores her father, Otto Frank. He's the person she leans on the most, and the person she most wishes to please. She's definitely a "daddy's girl." She feels like she can talk to her father about anything and even has a cutesy nickname for him: "Pim." Like Anne, Otto is a perpetual student, inhaling books, history, and news, and he encourages these interests in his daughters, as well as in Peter Van Daan. He gives Anne the diary as a birthday present, encouraging (and innately recognizing) his daughter's need to creatively express herself through writing. He also ensures that the kids have stuff to do: "Miep will bring us books. We will read history, poetry, mythology" (1.2). And he helps them continue their schoolwork, "Anne, you got an excellent in your history paper today… and very good in Latin" (1.3).
We can see from where Anne might have gotten her joking good humor. Otto is the only one who plays along with Anne's prankster clowning, becoming her partner in imaginary waltzes and her character sketches such as "Tom Cat." But as adorable and squishy as Otto is, he is also brave. He volunteers to go down into the business offices when the thief breaks in, saying "We cannot live with this uncertainty" (1.5), even though it could cost him his life
Otto is also sensitive to the needs of the others in the Annex. For example, he's quick to recognize Peter's dependence on his cat for comfort, and finds it a box to sleep in. He's also the sole source of logic and cool-headedness in every single tough situation the group experiences in the Annex. It is Otto who decides how to deal logically with the blackmailer, the thief downstairs in the business offices, and Mr. Van Daan's food thievery. Perhaps his greatest fear is that the Annex residents won't get along and the hideout will be for nothing: "We don't need the Nazis to destroy us. We're destroying ourselves" (2.3).
As much as Anne idolizes her father, she feels he sort of abandons her on one subject, her mother. Otto refuses to take Anne or Edith's side in their arguments, wishing only for peace between them and no hurt feelings. This makes Anne feel like she can't completely trust him and encourages her to look for a confidant closer to her own age, especially as she matures and finds that a girl needs more than her daddy to talk to.
As the only member of the Annex that survived the Holocaust, Otto Frank alone must return to the Annex and the memories it holds for him. He's the last character we see before the play's end. Parents or not, the audience feels great empathy for him as he reads the words his daughter wrote. As Otto Frank becomes humbled by what is expressed in Anne's diary and her words of positivity and light in a time of great darkness, we feel a sense of loss for him. It must have dealt this man a crushing blow to be unable to prevent the horrible tragedies that occurred to his family. However, we continue to look up to and respect Otto Frank for raising such a beautiful mind in his daughter.