I couldn't narrow down my post to just one comic, since both of them are so realistic, well made, and deeply personal. For those reasons, the two books have a similar ancestry. They are autobiographical tales, in high contrast black and white, that portray the pain and confusion of adolescence. Hopefully I can include enough analysis of both to do them justice.
I think they also share a kinship in their confusion with identity. Purposefully or not, both stories seem to be saying that a person is basically a product of his or her environment and influences. It may be inescapable, as the character Abellio in Epileptic claims.
Both Marji and Pierre-Francois (who later renames himself David), the main characters, are faced with terrible events surrounding them. Marji's problems are on a large scale (political unrest, social uprising, war, government oppression) while Pierre-Francois' are closer to home (turmoil within his family and friends). Both experiences occur during their formative years, and I think this is why the stories are so vivid and powerful in their memories all these years later.
The concept and development of identity is significant in both works. Hayden White's article Content of Form: Narrative Discourse and Historical Representation states that the purpose of narrative is to reflect on culture and humanity itself. Persepolis and Epileptic have very different cultures but the humanity is the same. White also points out that narrative is made up of a person's story, edited down to what they decide to include or exclude. Marjane Satrapi and David B. both cut down their narratives to the essentials of their experience developing as a person around very tough times.
Marji seems to be a bit more malleable than David and his siblings, but both imagine greatness for themselves. Already at age 6, Marji decided, apparently on her own, that she would be a great prophet. However, her ideals and views change from one period of life to the next. At first, she loves the Shah and believes he is appointed by God. Later, Marji strives for greatness by association. She is enthralled with the stories of her ancestors who were persecuted by the old regime. Quickly her love of the Shah disappears. When her uncle Anoosh arrives and relates tales of his communist past, Marji suddenly admires Karl Marx. She even sneaks out to attend demonstrations.
She is very proud of her uncle, not just because of his politics, but because he has suffered. After Anoosh is imprisoned and executed, she rejects God as her friend (a great departure from her earlier childhood) and declares that she is lost and without bearings (p. 70). When the war with Iraq begins, however, she is ready to fight the Arab invaders, and Marji draws herself wearing a military cap (p. 79). In this way, Marjane Satrapi seems to portray herself as always changing and a bit confused as she grows up.
Similar to Marji, at an early age Jean-Christophe (David's older brother) sees greatness in himself, but as an imaginary dictator like Hitler or Stalin. David himself wants to partake in bloody, historical battles and be a conquering hero like Genghis Khan. When the two brothers play with their sister, they treat her as Joan of Arc. War intrigues the two, but they never partake in one. The Beauchard family has a great many soldiers in it, but David and Jean-Christophe are relegated to childish fantasies about it. Marji has to see war up close, and eventually escape it by moving to Austria.
I suppose these are archetypes of adolescent fantasy. After all, nobody daydreams about being ordinary. But it is clear their fantasies, and thus their identities are created by the culture and events surrounding them. In Epileptic, Abellio claims that most people only utilize 1% of their free will (p. 139). Jean-Christophe is the perfect example, because his demonic illness, portrayed as a Meso-American serpent, is controlling him. It is ever present, and cannot be exorcised, despite all the efforts of doctors, faith healers, and other gurus.
That brings me to the alienation of character. What is the significance of alienation in both stories? In both, it can be an empowering device, and one that brings unexpected freedom. Jean-Christophe is first alienated from his friends (the "gang") because they are afraid of his seizures. Marji is alienated from her Iranian society because she wants to be an ordinary, educated, Westernized girl, but the new religious regime forbids such behavior.
Eventually Jean-Christophe goes away to a school for disabled kids and finds freedom from his family, from macrobiotic diets, and from mad scientist doctors. He rejects his family and tries to stuff the demon serpent into his locker. Marji, by contrast, is sent away by her parents to a foreign nation and is sad at the departure. They are both faced with a pivotal time in their lives, where independence is sudden and hard to deal with. However, this alienation means a freedom from oppression, and a freedom to be yourself on your own terms, in a new stage of life.
These two aspects of storytelling (identity as a result of environment and alienation from that environment) may seem to be contradictory, and perhaps it is, but that's life.