Wow. I really love a bunch of these ideas here. I have always been a massive fan of firefly/serenity and have just recently rewatched the series again.
First of all, my criteria for what a third season would have to be that it would be post "Serenity" and sticks to the storyline from there. It would be by far the easiest to do since there's no way they could use new actors to continue on with. So a post serenity timeline makes sense. River can be just a bit more grown up and all.
Another bit of criteria would be that it should be one season that has a pretty closed story arc by the end. No need to leave another loose ended season that might not come.
I feel that River and Mal would gain a bit stronger of a father daughter relationship, as set up by the endings of season one and the end of serenity. This would easily come about as River would likely become Serenity's principle pilot now, with Mal up in the cockpit alot. River would retain her 'Aloof' state of apperance but slowly become more deliberate in her actions, gaining control of the training implanted in her by the alliance, possibly even a few more "secrets" by some point.
The season would start out with nobody being the wiser about who aired the Alliances dirty laundry. But quickly small uprising would begin to be seen about the system. Eventually it would be found out that Serenity and crew were the ones responsible. The new browncoats movement would try to get him onboard. But of course Mal will refuse, saying something about needing to protect his own.
This whole time, Zoe will have been taking Wash's death pretty hard. She will be distant. Prone to attacking Alliance at any chance (small stuff, like a random guy saying ANYTHING Pro Alliance) basically trying to get herself killed. When the New Browncoats come looking for Mal as a leader. Who they will get instead is Zoe, who needs to leave Serenity to help her deal with the loss of wash. In the long run this will be for the best, Zoe always being the cool head and strategist to Mal's "kick em in the nuts, first time every time, no matter the hurt you get doing it" approach.
Now that this has happened. We're getting a pretty sparse crew here! Time to bring in a little fresh blood. Maybe a small time group that Serenity rescues from a situation. Or maybe one or two strays from the past. In any case, I think one of them needs to be a bit of a badass chick, to make up for the loss of Zoe as a strong fighter. This should give Jayne a bit of a love interest, I think that would just be funny as hell, Jayne getting all googly eyed and doing stuff to be genuinely nice (can you imagine him giving a lady flowers). Maybe bring on a guy who is a Cheff getting passage, but end up getting hooked on like the original passengers. Maybe he has a secret past life of a ninja or somethin to make him good with knives ;-)
So. Regular hyjinks occur. They get jobs. Character development stuff. Mal and Inarra finally start to cozy up to each other, things get in their way, some great ideas have already come for that. Simon and Kayle are together. They probably wind up getting married or engaged. Jayne, new people, others do their stuff as needed. All is good.
All the while the browncoats have started to build up. With the alliance trying to siege them into submission by cutting supplies and support to the outer colonies where they are based, they finally push to far somewhere, bringing back complete war, with Serenity stuck in the middle. Mal eventually gets stuck with a choice with either helping the alliance, or retaking his role as a browncoat. Of course, hilarious line and mayhem insues, and Serenity becomes the "ceremonial flagship" of the browncoat movement, always being the little ship that could, sort of deal.
In this short war, the Alliance has done some
Evil things (think weapons of mass destruction, killing whole populations to get a small suspected browncoat group etc.) and has turned even many of the inner planets citizens against them. Zoe (who is now General or Admiral, something of the sort) calls on Mal to do what he is best at. An overly stupid, almost one way attack on the central alliance leadership that nobody else could ever make work.
Leading a small strike force of browncoats, Mal and crew go after the central alliance leadership, based in some well hidden super base somewhere (can you say deathstar?) Thanks to Rivers gleaming info about this place off of Parliment people while being experimented, they feel like they might have a shot of pulling the whole thing off.
With River as guide, Kayle doing her on the fly rigging and stuff to get through jams. Simon being combat medic. Jayne (and hopefully girlfriend? :-D) at the charge of the assault team. Zoe the commander of the main battlefleet as distraction to give them a chance of completing the
Mission.
Of course. They do whatever it is to be done to cripple the alliance military in the battle. The Browncoats, having won, feel like they should take over, but Mal, in his wisdom? Basically says that by doing that, they will have become the new alliance, and this would just be the start of a new uprising to come. They find some way of making life better for everyone, and peace reigns through the universe. The end. Oh and Mal and Inara finally get, and stay together. If Inara doesn't get shafted at some point lol.
If you can't tell I'm a bit of an action guy, so the whole final battle may be slightly big and exciting. Lots of good blowing stuff up. Things that firefly/serenity is quite good at. Unfortunatly being a leaf in the wind will probably only work once :-( sorry wash. Serenity might get blown up, some kind of symbolic thing for Mal to be able to put the old rebellion behind him and just live his life. ( Like he would become a farmer, lol. I see a short retirement for him)
So, that's kinda a beginning and end of what I think would be a great final season of firefly. Few holes, if any holes left to be filled. All is pretty well with the verse, with lots of good lines and explosions.
