I often see critics of stories in regards to agency of the characters in the stories they read or watch. Some times, I've found myself agreeing with their stances, other times not so much. Anyway, what does character agency in fiction mean to you. Please feel free to give examples.
Usually when I use it, or I hear others use it, it refers to how much direct control a character has over the course of their lives/actions. A character with little to no agency, doesn't make any choices for themselves, and just goes along with the crowd. They aren't ACTING, they are simply REACTING to events that happen to them. This is often a trait of the supporting cast of a protagonist. Protagonists, by nature of them being the driving force of the main story, are chock full of agency, because they are the ones the story shows making decisions, taking actions that have direct ramifications to the immediate situation, and to the long term story arc.
To use a few examples off the top of my head. Princess Zelda is an example of both a character with no agency, and with plenty of it, depending on which game.
In the classic Legend of Zelda game, she has zero agency, because she's just a trapped person that needs rescuing. She takes no actions at all over the course of the game. In later titles, where she's actually a character that takes part in the games, she has more agency, as she is shown to be doing things that directly move the story along.
Now this doesn't mean they can't fail, having agency isn't a guarantee that everything you attempt will be a good idea, or succeed, it just means it's something the character initiated themselves.
Princess Leia in New Hope is a good example of a character with agency. While she does spend the first half of the film as a Damsel in Distress, she's not entirely helpless, or unable to direct events. She is introduced evading the troopers, and smuggling the plans off the ship via R2D2, she then attempts to escape, killing a trooper, and then is captured. While captured, she attempts to negotiate and deceive the Imperials, by tricking them to attack an abandoned base, in order to save Alderan. It doesn't work, but it is an action she took, of her own choice. Later, when she is rescued, and they are pinned down, she is the one that snatches up a blaster, and makes the call to escape via a garbage chute. She doesn't just meekly hide behind the guys and let them come up with the escape plan. A character with low/no agency, would just be attached to the more dynamic characters, and just follow their lead.
The question of agency, as I stated above, is mostly an issue for the secondary cast of a story. It's pretty much impossible for a protagonist/main character, to have no agency, as they are the focus of the story and driving it forward. And lately, this issue of agency, is usually brought up with talking about female characters, as they are, traditionally more prone to being characters in stories that don't drive it forward, and are just there, usually as motivation for the heroes (we have to save the princess!).
To give a gender flipped example, Katniss has tons of agency in the Hunger Games, because she's the driving force of the narrative, but that drunk character/mentor guy, doesn't really do much directly in the first movie (as best as I can recall). He's mostly there to be a cautionary tale for the 2 lead characters, showing them what it looks like to be a "Victor." And to provide exposition to the audience about what to expect in the Hunger Games. The bakery guy that is in the games with Katniss (sorry I forget his name), has some agency, but not as much as Katniss, though his agency is more subtle. He tricks and deceives the gang of other kids to leave Katniss alone, giving her time to escape. He provided Katniss with extra food prior to the games, despite it being a risk to him personally. He...made himself into a rock cake (*facepalm*) to hide from other players, etc etc. So he took actions that directly effected the overall outcome of the story, but not as many, or as far reaching as Katniss.