Iroh jogged towards the dark spirits, fists clenched. He didn't look back. Instead, he focused on keeping a steady, even pace, timing his steps to counts of four. He was used to using physical activity as a way to calm his emotions, and every muscle in his body was screaming for him to run as fast as he possibly could until he dropped unconscious. He couldn't give in to that urge; he needed to save his strength.
Let's just pretend it never happened. Asami's voice, casual, almost joking. It wasn't enough to tell him no. She'd erased him.
At least he wouldn't be going into a fight, potentially his last fight, with half his brain thinking about how Asami had felt pressed up against Katara's kitchen counter and wondering when he could do it again. Instead, frustrated, embarrassed, and surprisingly hurt, he could simply focus on burning the shit out of anything and everything he encountered. Tired though he was, Iroh found he had energy for that in spades.
In some ways, he was glad that he'd finally forced himself to talk to her. At least now their relationship was clear. If he was honest with himself, Asami's answer wasn't wholly unexpected, either. He'd known that she was still involved with Mako, or at least had feelings for him. He had thought, maybe, something in the way she'd looked at him once or twice, or the way she had hugged him in the hallway at Katara's house... but apparently that was only wishful thinking. He had no idea what Mako had that he didn't, but he knew enough to accept a clear defeat. Asami may have kissed him in the moment, he couldn't deny that had happened, but she had said herself that they were both under a lot of stress. That could easily be reason enough, especially since he'd surprised her. Spirits, Iroh had surprised himself.
Besides, a dark part of his mind whispered, according to Unalaq all people from the Fire Nation looked roughly the same. Maybe, in a weak moment, to Asami he'd simply been close enough. He recoiled at the thought. Whatever her reasons, at least he could avoid making a further fool of himself. If he lived through the next 15 minutes, that was. Based on the number of dark spirits he saw as he approached, that was looking like a very big if.
Iroh was close enough now that he could see individual spirits. The variety was astonishing, and the spectacle helped to take his mind off his thoughts. It wasn't that he hadn't believed Asami's description of the spirit army, but it was another thing to see it for himself. He'd seen the occasional small spirit all his life, but in his experience those were generally rounded and colorful. By contrast, these spirits were black and twisted, their jagged edges and sharp lines glowing with poisonous colored light. Many of them seemed to resemble versions of fauna native to the South Pole: arctic hippo and camel, buffalo yak, and polar bear dogs similar to the one the Avatar rode. But there were also many animals he'd seen elsewhere on his travels, like platypus bear, camelephants, fox antelope, and even one of the Fire Nation's rare komodo rhinos.
Alongside the animal shapes floated things unlike any creature Iroh knew. Anywhere between six and 15 feet high, these enormous spirits were vaguely man-shaped, but with bodies made entirely of geometric shapes. Triangular or trapezoidal heads sprouted from rectangle bodies, and ropy, wiggling lines replaced arms and legs. As flat and pitch-black as the animal spirits, they were some of the most bizarre things he had ever seen.
As he approached the dark spirits, Iroh started banking right. He could feel them now, a heavy presence in the back of his mind, a low, simmering sense of anger and disturbance that was not his own. It was exactly like what he'd felt in the seconds before the bison spirit had appeared in Fa Re, but amplified. He estimated there were several hundred of them altogether, traveling in a loose ball across the plain, but at a distance it wasn't hard to flank them. Although they appeared to gallop and run, he saw that they never touched the ground, instead hovering about a foot in the air. As Asami had predicted, most of them seemed to be making straight for the south entrance to the city. All he had to do was spur them along and take down as many as he could in the process.
He was up alongside the spirits by now. Iroh reversed direction, jogging backwards to keep abreast of them. As he did so, he saw a group of a dozen or so start to break off, heading in his direction. Either they'd noticed him, or they were heading for another point on the city walls. Regardless, it was what he had been waiting for. Iroh took a deep breath and focused.
Let's just pretend it never happened.
"Forget this," he growled, and unleashed his fire.
Two white-hot balls of fire shot out of Iroh's closed fists. They hit the lead spirit, some kind of bear, in the center of its shaggy chest. A nearly two-foot area of its torso simply dissolved, as if it was smoke blown by a stiff breeze. The spirit shuddered, but kept advancing, its chest re-forming as it came. To Iroh it looked slightly smaller. That was good; it meant Asami's theory about its healing abilities was probably right.
As it moved, he was astonished to see that the spirit behind it, one of the odd geometric ones, was re-growing what passed for one of its shoulders. Apparently, whatever the spirits were made of was insubstantial enough that he could damage multiple creatures with one blow. That, thought Iroh, could change the game entirely. Maybe he'd live through this after all.
Iroh lined up another shot, taking a few extra seconds to look for areas of overlap. This time, instead of a ball of fire he released a steady stream of flames from one outstretched hand. It hit the bear spirit in the face at nearly point-blank range. The creature stumbled as its head dissolved. Behind it, Iroh saw three more spirits stagger as parts of their bodies blew away like puffs of steam. One of them, a small deer of some kind that came up only to Iroh's elbows, started to churn and swirl, then faded entirely. One down, several hundred to go, he thought grimly, and then the bear spirit hit him in the chest.
The immediate feeling wasn't of pain, but of cold; the kind of deep, penetrating cold that makes muscles cramp and bones ache. For a brief moment Iroh couldn't breathe at all, and he was reminded forcefully of his terrible swim in the Southern Ocean. The blow knocked him back as he gasped for air, but he'd seen it coming and managed to control the fall, if just barely. He leaned into the hit and landed on his back with a thump, elbows under him. He stuck out one foot. Fire erupted from the sole of his boot, taking the spirit's hind leg off at the knee as it charged past.
The fire inside him eased the pain in his chest a little. His bruised shoulder throbbed. Iroh sucked in two big breaths, then dived to his right to avoid the spectral claws of some kind of giant cat. He skidded on his side and the scrape on his hip flared in pain. This wasn't going well. Even firing on a few spirits at a time, he was spending more time getting out of the way than hurting them. Meanwhile, the bulk of the dark spirits were simply passing him by. While his goal was to drive them to the gate, he didn't like the idea of having Asami stand between several hundred spirits and their goal. He had to wipe out a lot more of these things, and fast, if she was going to stand a chance.
He only knew one other way to hit more than one spirit at a time. If he could lightning bend, he'd be able to arc across several targets at once, and with far more power than fire alone. It would tire him out quickly, but Iroh had the feeling this battle was more of a sprint than a marathon. It would be worth his burning out fast to gain the initial advantage, especially if it would give Asami a better shot later on.
Lightning bending was to firebenders what metalbending was to Earthbenders; Iroh estimated less than one in ten firebenders could do it at all, let alone master the technique. Iroh had learned from Fire Lord Zuko himself though, and had both the raw power and mental disposition for the task. He quickly stood and tried to clear his mind, to empty himself of all emotion. He focused on feeling nothing besides the energies inside him, the separation of the yin and yang that together formed the element of fire. He breathed in and felt the tension rise as those powers were stretched apart, poised to snap back together and through him in an arc of nearly pure energy.
Iroh moved his arms in a circular motion, aiming at a knot of dark spirits less than ten feet away. As he released, Asami's green eyes flashed across his vision, clouded with disappointment. Fire exploded from Iroh's fingers in a ball nearly five feet wide. The force of the blast knocked him backwards, and he almost lost his balance. He staggered, then whirled to sidestep the charge of a dark, misshapen arctic camel, its nose and humps glowing with sickly orange light. He closed his eyes, took a deep breath, and tried again to focus on the energy inside him, to feel nothing. He moved his arms to channel the lightning, aiming at the camel's broad back.
It's okay, Asami said. We're all a little keyed up.
A gout of flame even larger than the last burst from his hands, and this time he did go down. He rolled to avoid the legs of one of the geometric spirits and managed to use the momentum to at least wind up on his knees.
Iroh was stunned. He felt like he'd been punched in the gut. This... wasn't good. Lightning bending required calm, balance, detachment. He'd always had an aptitude for those kinds of tasks, and had picked up the rare talent quickly under his grandfather's instruction—far more quickly than the former Firelord had himself, apparently. He'd never had it fail. What was wrong with him? Was he so inadequate now that he couldn't even—
A huge spirit, another of the tall man-shaped ones, kicked him from behind. Pain shot through his right leg, the one that Aunroch had struck, as he twisted. Iroh fell over on his face in the snow, his whole body paralyzed with deep, numbing cold. The dark spirit simply stepped over him as he watched, as if he were no more of an obstacle to it than a large rock.
Some hero, Iroh thought bitterly, as the spirit lurched eerily towards the gate, its three legs never touching the earth. Except... now that he looked, it wasn't going towards the gate at all. Most of the dark spirits weren't. Rather, it seemed that the bulk of the group had instead veered slightly to the west.
Too late Iroh realized his mistake. They had been sure that the spirits would attack the weakest target. It had made perfect sense. They had been thinking of this in terms of entrances to the city, and until now it seemed like they had been correct. But they hadn't factored in all of the information.
At the spirit portal, Asami had assumed that the dark spirits had gone after Tenzin and the others because she'd presented the harder, more aggressive target. And now, she had been right again about them choosing the South Entrance to assault. But Iroh realized that it wasn't for the reason they'd thought.
The missing piece was Fa Re.
When they had battled the dark spirit in Fa Re, Iroh had pushed Asami, who had left her glove back at the camp, out of the way. After that the creature had all but ignored her until she'd called to it, despite his laying into it with a steady barrage of fire. Distracted by his emotions, Iroh had completely failed to see the implication. Power isn't everything, he'd told Asami, but that was only true if you could trump it with strategic ability. The spirits didn't have strategic ability, not really. In some ways, they were just like Chelin, Aunroch, and every other arrogant bender. With most of the Southern Water Tribe resistance out of action, and waterbending still a rare skill in the South, anyone left defending the East Entrance was probably a regular soldier.
Given the choice, the dark spirit in Fa Re hadn't focused on the weakest link at all. It had gone after the most powerful bender.
They all had.
Katara.