The Firefly fanfic Forward has plenty, judging by the responses of the reviewers.
The general consensus is that some of the best moments come at the end of the story arc "Mosaic." The crew has been captured by pirates, only to have Jayne and River save the day. Jayne does his part by setting himself on fire and then breaking an opponent across his knee. Meanwhile, River is confronted by the pirates' resident martial arts master, who is approaching her while imagining her to be a Worthy Opponent who he can test himself against. He charges at her, preparing for an epic martial arts duel....and River shoots him in the throat.
And then, while standing over all the dead bodies, River demands Mal bring her chocolate.
"Last Man" indicates that Jayne got the whole "set myself on fire" trick when the Brit was set ablaze by an incendiary bomb and charged him with a knife while on fire.
Jayne gets a lot these. For example, in the "Condor" arc, Jayne Scope Snipes an Operative from two kilometers away, while on top of Serenity.
And in the Third Interlude, Jayne manages to board a gigantic monster truck chasing Mal and the rest of the crew via an ATV (with the scene emphasizing just how insanely difficult that is) and then climb up and kill all the goons inside with just a revolver and brutality.
Are we leaving out the part where Jayne starts slicing off Niska's fingers one-by-one once he gets loose? And this is after he and River hatch the Batman Gambit that got them loose in the first place, using nothing but silent gestures, code words, and River's telepathy.
And shortly afterward, Jayne kills a Hand of Blue after an extremely vicious fight, caving the man's head in with a bedpan before slitting his throat with a scalpel.
At least until she gets hit by paralyzer darts in the middle of the Reaver horde.
And the chapter immediately afterward, wherein Shepherd Book pulls a Big Damn Heroes moment when he charges headlong into the Reavers about to rape and eat River, wielding a sword samurai style and shouting Bible passages as he cuts them down.Badass Preacherdefined.
And right after that, Simon does his own rescue of Book by bashing a Reaver's head in with a rifle.
Followed by Wash getting his own officially recognized Big Damn Heroes by venting a good deal of plasma into the Reaver ship with piloting descrbed as a hippo doing an Olympic gymnastics routine.
And of course one of Mal's plans working out perfectly for once, luring the Reavers into the gravity-less cargo bay before opening the lower hatch, then scraping against an asteroid to take care of the few survivors.
Mal doing what he doesbest in the final fight in Mosaic by turning tables on Ott and his goons as they have him bound, beating the snot out of them and delivering this editor's new favorite one-liner:
Mal: You want my gun so bad, you can have your fill of it.
Added benefit to that is Ott really likes antiques like Mal's gun. So, Mal gives Ott all the gun he would ever want - by shooting him in the back when he runs away.Do not fuck with Mal's crew.
The climax of "Silver" has these back-to-back for just about the entire crew. Among the highlights, according to the reviewers:
Wash, Zoe, and Book improvise a giant bomb out of the mule and drop it on a ship that's trying to shoot Serenity down.
Mal, Jayne, and Kaylee escape from a mansion full of angry security guards, invading soldiers, and a massive heavily armed gunship via flying carpet. While naked.It Makes Sense in Context.
The character of Echo gets one in he "Second Interlude" where he masquerades as a drunk to get the drop on Jubal Early, and thoroughly beats the crap out of him, laying him out unconscious in a single second.
We cannot forget Corporal Ash Frye who manages to put up a heck of a fight against Early prior to Echo's arrival. This editor wonders if it's karma playing catch-up...
In the "Charity" arc, we have Zoe managing to almost singlehandedly fight off half-a-dozen armored, well-armed and well-trained mercenaries with just her shotgun and a knife. And this is while she's pregnant.
Two chapters later, Zoe shoots down a heavily-armed gunship with just a lever-action rifle.
In "Hunt," Zoe tells Simon he's going to have to stay behind because she's afraid he'll be too emotional while confronting Kathryn, as she's the reason why River has gone missing. In her own words, Simon will have to be "cold" and control his emotions. He then quietly and calmly lays out how "cold" he's been throughout the series when it comes to saving his sister, particularly when rescuing her from the Academy and when he helped Zoe and Mal interrogate Niska's mercenary in the first story arc.
The one thing the series has really lacked is a definitive moment for Kaylee....at least until the climax of "Hunt," where she kills a Hand of Blue with a power loader. In the same scene, Wash and Inara show their chops too, managing to keep the Hand of Blue busy for an impressive length of time despite not being real fighters.
Zoe calling on her soldier instincts to resist Kathryn's Mind Rape long enough to kill her.
River butchering a Hand of Blue after Simon lets her use Laertes, which we're reminded earlier is the first time she's ever gotten the better of one. And followed by her effortlessly taking out two more enemy soldiers.
In the Fourth Interlude, River has a steady string of awesome moments, generally due to drawing upon the knowledge and memories of her friends to improvise and adapt to changing conditions, and sheer, cussed determination.
When a pirate ship picks her up and starts chasing her, she uses Wash's knowledge of spacecraft to disable the pirates' larger and more heavily-armored vessel.
After crashing during the aforementioned chase and breaking a few ribs, she kills four of them within the span of a single second with four lethal shots, causing the rest to immediately run. Then she marches overland through the desert on those broken ribs, pushing on through her encroaching dementia with sheer stubborn will, borrowed from memories Mal and Zoe and Jayne.
When the pirates come back for another round, she draws them away from the nearby town to keep civilians from getting caught in the crossfire, and in the process gets hit by the pirates' thrusters, resulting in a broken back and legs - but she's still able to make the pirates back off when they close in on foot by drawing an incendiary grenade with a primed dead-man's switch. Ultimately, it results in a Blast Out where she has to shoot the pirate captain dead, but only after he both shot her int he stomach and she was apparently given a concussion by a ricochet off her skull. Now that's a Determinator for you.
Quote River's own mental analysis:
Catalogue of injuries: hairline fracture in shin. Multiple fractured or broken ribs. Lacerations, bruising of back, vertebrae, possibly wrenched shoulder and back muscles. Bullet lodged in gut, precise location unknown. Head trauma, ninety-plus percent probability of concussion (postulate round ricocheting off boulder and bouncing off skull, or maybe shrapnel knocked loose by same) Bruised jaw. Sunburns.
River and Jayne's escape from Niska's ship in "Unfinished Business" is made, on equal parts, of brutality and awesomeness.
Mal weaponizing Serenity's exhaust to weaken an Alliance's ship so much that it weakens the glass separating the bridge from the Black and, three armour-piercing rounds later...
"Last Man" is pretty much just a continuous stream of reasons why Jayne Cobb is not to be fucked with, at any age.
In the flashback, when ambushed by the Six Rifles at a diner, he manages to not only escape all six of the assassins (with a little help from the American) but he also survives an explosive trap left at his apartment, a lengthy car chase, and getting run off the road into a ravine.
When the Brit and the Frenchman close in on him, he uses a bit of ingenuity to lay a gasoline trap for them and catches them both in the explosion. This one also becomes an awesome scene for the Brit, who not only survives the explosion, but is so pissed off he charges Jayne with a knife while on fire.
The rest of the Six have nearly run Jayne down on a dam spanning a river. They start across the dam to chase down the wounded teenager, and walk right over the mining explosives he's strewn over the dam. At that point, the explosives blow the dam apart and clause it to collapse, taking out the Syrian and scattering the rest of the Six.
Note that the Frenchman takes the worst part of all of the above, and is still standing and even manages to shoot Jayne in the leg immediately after washing up.
In the present, Jayne manages to pull Konstantin and his goons off Wash by using a stream of bad puns and jabs at Konstantin's missing limbs. Then, when they close in on him, Jayne uses his old tricks: he kills one of Konstantin's men with a precision shot to the neck and then lures the rest into an ambush - except when Konstantin thinks it's going to be another explosive trap, Jayne instead knifes the bounty hunters' machinegunner, takes his weapon, and goes Guns Akimbo with it and Vera on the rest of the team.
Wash is no slouch in "Last Man" either while being chased by Konstantin's ship in the slow, unarmed shuttle. When he realizes he's being chased by several tracking drones, he actually turns around and rams them apart before, in a pretty balls-out crazy act of piloting, matching speeds with the last one and grabbing it in mid-air with his bare hands!
Later on, he saves Jayne as he lays dying from his wounds, and when the Cossack leaps onto the shuttle, Wash shoots him six times in the chest.
In "Wrath", River's Badass Boast right at the moment where she reveals that the whole "interrogation" thing was a trap.
River: You have made multiple assumptions, based on fallacious reasoning, which I find hilarious. First, you think I am still an emotional wreck. You believe that I am unstable, ineffective, defeated. That is a reasonable but terribly erroneous assumption. I am functional. (...) The second fact is that you assume physically restraining me will keep you safe. You should know better by now that restraints are irrelevant. Because I can kill you with my brain.