Where does Katniss start?

District 12, hunting illegally in the woods outside the fence to feed her family. She's 16, pragmatic, and primarily concerned with keeping her mother and sister alive. The world's injustice is fully visible to her — she knows exactly what the Hunger Games are — but her response to that injustice is survival, not rebellion.

What forces her into the symbol role?

Prim's name in the reaping. Katniss volunteers to take her sister's place without calculating the consequences. This instinct — protect Prim — is what drives everything. The Capitol and the rebellion both see a symbol in that moment. She just saw her sister.

How does the Capitol turn her into a symbol?

By requiring her to perform — the chariot scenes, the interviews, the fire dresses. Every performance the Capitol stages to make Katniss spectacular simultaneously makes her more threatening. Her genuine self (hunter, sister, survivor) is more magnetic than any manufactured celebrity because it's real.

How does the rebellion use her?

More cynically than she initially understands. Coin and Plutarch want the Mockingjay as propaganda — a face for the revolution. Katniss's actual opinions, actual trauma, actual agenda (get Peeta back; protect her family) are inconvenient. They manage her as a political asset.

How does her arc end?

She kills Coin, not Snow. After Snow is captured and available for execution, Katniss chooses Coin as the target — recognizing that Coin represents a perpetuation of the same system under different branding. This is her most significant autonomous act in the series. Not saving Prim (who dies anyway). Not killing Snow. Refusing to let the revolution install a new version of what they were fighting.