Objects in Space was the last Firefly episode to air, and my absolute favorite before my rewatch. Finally, we get something of a peek inside River's head, and although the villain-of-the-week gets far more screentime than River herself, it's an episode of transition for her, the move from victim to victor, and from "object" to "subject" in the narrative and the crew.
Objects in Space is the episode where River stops being an "object" in the crew, something to be argued over and protected and viewed from other people's perspectives, and starts being an active subject in her own right. The episode's opening moments make this transition clear, as we see the ship entirely from her perspective, including the way she hears people's thoughts, and the way she misconstrues what is happening around her. It's all a bit heavy handed, as the camera zooms in on her bare feet as she walks through the ship, and there's no explanation of why she sees a branch surrounded by leaves instead of a gun, except that the imagery is pretty... but it is pretty, and after many episodes seeing River and her emotions entirely from the outside, it's refreshing to see her move away from the helpless waif stereotype and turn into someone we can empathize with. We are finally allowed to put ourselves in her shoes (or lack of shoes), and see the ship through her eyes. By the end of the episode, meanwhile, River has successfully hatched a plan to save everyone on the ship, including going out into space in a suit, breaking into Early's ship, hacking all of Serenity's comms and locks, and tricking her hunter into becoming the hunted instead. In fact, the plan only goes wrong because of the problem she's faced all along -- her brother, for all his love and sympathy and desire to protect her, simply doesn't understand her or what she's trying to say or do. He doesn't trust her to act alone.
And in between these two moments, the episode really highlights how much of an "object" River has been to the crew. They take the gun from her, but after it's been disabled, they barely even acknowledge her. They don't even ask her where she found it. When they have a meeting about River and her future, they don't include her, leaving her to balance, eavesdropping, on the bridge below. River's heartbreaking speech that the crew "didn't want her here, so she melted. Melted away," along with her later comment that she will "fade away," suggest that she too is aware of her passive status, as something that could easily fade away rather than a person who is present, who fights and acts and commands her environment. But in this moment, River is only playing with the idea. She gives a tragic speech about how she melted away, but she's actually tricking everybody, sitting on Early's ship and laughing in delight at her own cleverness. When she says she will sacrifice herself and fade away, she's lying to enable her plan to kill Early herself. She takes an idea that seems to have represented her from the beginning -- the waif girl, the victim, weak and crazy and unable to act for herself -- and she uses it to her own advantage. Because, ultimately, she is not that girl. She's a genius girl who loves to dance, who wants to find her place, and who also happens to be a psychic assassin. And although she became a psychic assassin because the government also used her as an object, manipulating and rewiring her brain, she's also able to take these new skills and use them as her own.
River spends the entire series being an object, and Objects in Space is finally her time to show the other characters, and us, that she is far more than that. Shame that the show ended immediately after this, so we never got chance to see where River's character would grow (although Serenity, of course, offers a more condensed version).
As a final episode, Objects in Space is pretty great. It certainly addresses some of the problems with River that the series had up to that point -- problems that perhaps would not seem so problematic if the show had gone on to have five seasons, making it "slow build" and "character growth," rather than the vast majority of River's narrative. As things stand, however, I'm still not convinced that River could have been a fully developed, fully engaged character... but the potential was there, if only we'd had chance to explore it.