Grandma is a very influential figure in Marji's life. She lies to the soldiers about having diabetes so that they can dump all the wine in the toilet; she keeps her bra fresh with lavender; she tells Marji that she soaks her breasts in a bowl of ice water for ten minutes every morning and night, to keep them round and firm. Oh yeah—and she tells her to "always keep your dignity and be true to yourself" (19.55), which is maybe—maybe—more important than wine and boobies.
This whole keeping her dignity and being true to herself thing is probably the most important lesson for Marji, and it's also the most difficult thing for her to achieve. Marjane thinks of her Grandma while living in Vienna, when she "managed to deny [her] nationality" (24.35), and she uses that memory of her grandmother to assert herself and feel good about her identity.
However, Marjane backslides a bit later, after moving back to Iran. She ends up turning in an innocent man to avoid getting herself taken away during a raid. She relays the story to Grandma, thinking it's funny, but Grandma's not having it. "I think that you're a selfish b****! That's what I think!!!" (33.46), she says. Thanks for the reality check, Gram.
Grandma reminds Marjane that her ancestors fought for freedom, not for imprisoning innocents, and this reminder is exactly what Marjane needs. She loves and respects her Grandma, and, hey, Grandma is always right. Marjane decides that she needs to act in a way that will ensure Grandma will never yell at her again.
Marji is probably the most sad to leave her Grandma behind when she goes to Vienna. We think Grandma is sad too, because she can't even bring herself to accompany the family to the airport. Grandma is also the last person in the book Marjane talks about, telling us that after she (Marjane) returned to Europe for good, she only saw her Grandma one last time. "Freedom had a price" (38.88), she says. In this case, the price was losing contact with one of the greatest influences in her life. Do you think it was worth it?