Thank you all for sticking with me! Just three chapters left. Based on a Ash9's feedback, I also added a tiny little scene in the previous chapter for Gwaine to see Merlin alive and well before Merlin effects their escape…

THE WATER WITCH AND THE BLACK DOGS
By TIPPER

CHAPTER TEN: WATER VERSUS FIRE

They reached Thiernan's camp just before the sun rose, cold white light blanketing the hushed space. Half the rhododendron bushes had been flattened, the ground churned into mud, and at least a dozen bodies were spread across the ruined hilltop. Every single one of them looked bloated and popped, as if they'd been burst from the inside out.

Merlin pressed his sleeved arm to his mouth and nose, trying to block out the smell, while Pieter and Gwaine did a quick sweep. He'd been left with the horses, and he was having a hard time keeping them calm. Dragging them around by the reins, he tried to see if any of the mercenaries near him were still alive. He knew, pretty quickly, that it wasn't worth checking.

Gwaine ran up to him, his face pinched. "Thiernan's not here. Neither is Scarface. They must be retreating. My guess is, as soon as you freed Peg, Thiernan knew. He left these men behind to slow her down, while he and a handful of others ran away."

"Ran away where?"

"To where he feels safest," Pieter said, joining them. "He'll go home."

"Home," Merlin repeated, eyes widening slightly, handing each man the reins to their horses. "You mean, his castle?" He looked at Gwaine. "Elyan and the others are still there."

"As is Clara," Gwaine said darkly. "We have to warn them. Get them out of there somehow."

Merlin frowned and looked up at the silvering sky, judging the time. "If we leave now, on horseback, we might just make it ahead of them."

"Even if we do get there first," Pieter said, "we're not going to be able to defeat both Peg and Thiernan by ourselves. We couldn't even take on one of them."

"What do you suggest?" Merlin asked.

"You two head to Thiernan's castle. Get as many people out of there as possible—if you're lucky, you'll manage it before either Peg or my brother shows up. Then it's just a matter of getting them across the border into Camelot. If Peg and Thiernan are distracted trying to kill each other, you should have enough time to do it. I'll ride as fast as I can to my father, to gather an army. If I head straight east from here, I should be able to get to the citadel in Mercia within a day and a half." He frowned. "I won't let my kingdom fall without a fight."

Gwaine nodded, swinging up into the saddle. "Sounds like a plan." He reached out to shake Pieter's hand. "Good luck."

"You too," Pieter replied, taking it warmly. "And don't do anything stupid, like trying to take either of them on without me."

Gwaine smirked. "Us? We never do anything stupid." He looked at Merlin. "Do we?"

Merlin just shook his head.

…

…

They were about halfway back to the castle, the sun just cresting the top of the trees, when Gwaine pulled up short on the road they'd been following. A stream snaked across it, emptying down into the valley to their right, and the mud surrounding it was filled with footprints.

"We're only a little bit behind them now," he said, pointing to the marks on the road that, frankly, were fairly uninformative to Merlin. "Those prints are fresh—less than an hour, probably a lot less." He peered down the ridge road. "We don't want to catch up with them."

"Can't disagree with that," Merlin said.

"Thiernan and his men are on foot, so they'll be taking the most direct route—this road along the ridge. Peg will likely be right on their heels."

"So what do we do?" Merlin asked.

"If we want to avoid them both…we have to avoid the road." He nodded towards the valley. "There's really only one option."

Merlin frowned, shuddering slightly. "You want ride through the valley of the black dogs?"

"It's the quickest way. On horseback, at a gallop, we should easily outstrip their pace."

"And if the dogs take offense?"

Gwaine shrugged. "We know approximately where they are, and we're a few miles from there yet. We just have to avoid where they live, cut up before we get that far down. With any luck, we'll have passed by both Thiernan and Peg, sliding past right under their noses."

Merlin lowered his head. "Risky."

"I know," Gwaine said. "Always is." He shrugged. "Come on. We can follow this stream down to the valley floor."

Merlin sighed, and turned his horse off the road, sending him down the hill after Gwaine.

…

…

The horses crashed along the river bed, the water shallow enough to make a decent roadway. Gwaine was low over the saddle, intent on the yellow turrets of his sister's castle in the distance. Only when he could see all four turrets would he start looking for a way out of the valley, but he promised himself that they'd go no further than that. If they did, they'd be too close to where the black dogs were, and also where the walls of the valley would be too steep for the horses to climb out.

He was so focused, he didn't notice until it was too late that the water in the river was getting increasingly shallow.

"Hey, what's going on with the water?" Merlin shouted at almost the same time as Gwaine realized that the river had all but disappeared in front of them, leaving fish and other creatures flopping in its wake.

"It's behind you!" a voice cackled from behind them, and Gwaine looked over his shoulder just in time to see the wave of water surging towards him. It slammed into them both, throwing them off the horses and onto the grassy meadow next to the river, the mud and dirt softening the impact as they bounced and slid.

This is getting a little old, he thought miserably as he pushed up on shaking arms and pulled out the sword in his belt. Next to him, Merlin was coughing, looking like he was having a harder time getting up than Gwaine was.

"You should not have followed me," Peg hissed.

She stood in the river, which was flowing again, staring at them coldly. The horses they'd been riding were already gone—probably tearing away through the woods in terror.

Gwaine finally managed to stand fully upright. "You gave us no choice."

"You had a choice. You could have returned to Camelot." Her gaze narrowed. "Now I will have to kill you along with everyone else." As she spoke, she stepped out of the river, walking to stand just a few feet away from Gwaine. Merlin was still on his knees, but his coughing was finally subsiding. Peg looked down at him before looking again at Gwaine. "You must know that you have no chance of defeating me."

Gwaine just smiled.

"Fine," she said. She jumped up suddenly into the air, and water flowed around her hands, forming an almost perfect sword. Gwaine had just enough time to get his up when she brought the watery weapon slamming down on top of him.

It shattered his borrowed sword into a dozen pieces and drove him down into the mud.

"Gwaine!" Merlin called out, alerting Gwaine enough to roll out of the way as Peg slammed her water sword into the ground where he had just been lying. He rolled further and up onto his feet, backing away to get around Peg's back.

"Heads up!" Merlin shouted again, and Gwaine snatched the dagger out of the air that Merlin had just thrown to him. He threw his body backwards as Peg slashed in his direction with her sword, feeling the dampness of it slide past his head as he bent almost in two. Turning around under the blade, he managed to get around her side as she suddenly staggered forward, as if tripping on something, giving him an opening he hadn't expected. Getting inside her reach, and sliced down, cutting through her side and part of her hip, spinning out of reach as she cursed in pain.

Peg had been raising her sword over her head again, but she let it go at his attack, hands going to her side. Gwaine's eyes widened as the skin he cut through simply closed back up again, as if it had never been split. Before he could react, she suddenly threw a fistful of water at his face, like being hit by a snowball made entirely of ice, the impact staggering him to his knees. He tried to bring up the dagger, but she was suddenly right in front of him; she brought two fists down, catching him on the left shoulder and driving him down into the mud again. His entire left arm went numb, the limb not responding at all as he scrambled out of her way.

And she laughed.

Struggling to get back to his feet, mud and blood sloughing off of him as he moved, he turned the dagger in his hands into a more defensive position. Without his left arm, he felt imbalanced, but he could still fight.

"All you are doing is delaying me," Peg said, stalking him. She had the water sword again, and he realized horribly that she was using it to mock him. Beating him at his greatest strength, and she wasn't even trying very hard.

"There has to be a way to kill you," he whispered, backing up on shaky legs.

She snorted. "It will take a lot more than one man to kill me."

Suddenly, she stumbled, as if something had shoved into her from behind. She whipped around, and Gwaine spotted Merlin on his feet behind her, hefting a rock in his hand. There was another by her feet—he must have thrown it at her. As Gwaine watched, Merlin drew his arm back to throw the second rock at her, and she reared up, the sword disappearing, the water swirling around her upraised arms like a monsoon.

Gwaine took advantage of the only distraction he knew he was going to get, and ran at her. At the last second, he leaped, planning to drive the dagger right through where her heart might be.

She twisted at the last second, flowing around him as he flew through the air, and he felt her get around his back and slam something hard against the side of his head. Pain flashed behind his eyes, worse than he had ever felt. And then there was nothing.

…

…

"GWAINE!" Merlin shouted, dropping the rock he was about to throw and running forward as Gwaine collapsed to the ground, lifeless. "No!" he yelled at Peg, who was still leaning over Gwaine's body where she had hit him with a rock – the first one he'd thrown at her – and, with a blast of magic, he just shoved.

She gasped, flying backwards away from Gwaine in a swirl of green and yellow. Before she could recover, Merlin was on his knees next to his friend, checking for a pulse, letting out a relieved breath when he felt it there…weak, but there.

"Is that all you can do?" Peg asked, the sneer in her voice clear as she stood up. "You think you can simply keep pushing me back? That little trick didn't help your friend much, did it?"

Merlin shook with rage, looking up at her. "No," he said. "It's not all I can do." Gritting his teeth, he got to his feet, fighting the pain from the sprained ankle he'd gotten when she'd thrown them from the horses.

"I'm not going to let you kill anyone else," he warned.

"Oh? Not even Prince Thiernan?" She smiled again, eyes gleaming with the tease.

"If you'd just wanted to kill him, you likely could have done it by now. But you're down here in this valley, almost hiding from him. Why?"

She flexed an eyebrow. "I told you," she said, lowering her head. "Because it's not enough for him to die. All of Mercia must suffer."

"But why? Why all of Mercia?"

"A Mercian believed he could shackle me, bind me to his will, and use me to make this kingdom powerful. For that, Mercia must be punished. Once I blight this kingdom, killing everyone and everything in it, all the people of Albion will know the price for trying to control Peg Powler. I am more powerful than any mere kingdom, and if any of them ever tries this again, they will suffer the same fate." She swept an arm out. "I am going to poison this river, poison every source of water in this kingdom, so that nothing will survive here for the next hundred years until I deign it worthy enough to let it return to life." Her lip curled in disgust. "And your magic is not strong enough to stop me."

"Maybe not," he snarled. "But something has to be." He pointed a hand at the grass along the riverbank. "Forbearnan." Instantly, the riverbank lit on fire and he used his mind to drag the fire across the entire bank, blocking her from reaching the water.

"You think that's enough?" she asked.

"I think Gwaine was right," he replied. "When you're away from a source of water, you're weaker."

She shook her head. "You don't understand, child. You think the river is the only source of water? Look around you. There's water in the air, in the grass under my feet, in the plants and trees around us." She twisted a hand in the air, forming a fist, and water dripped down her arm. She then threw an arm towards the fire, and water whipped out of her palm and put out a healthy section of Merlin's firebreak. He snarled, gestured at the fire, and it quickly reformed. She stared at him, and then started to run towards the fire, obviously intending to jump over it and into the river.

"Bæwylmas læcaþ!" he shouted, and the flames instantly rose higher, flaring well over her head, and she skidded to a stop, moving back. Snarling, she stood tall and Merlin could see the water rising up out of the wet, green earth to swirl around her.

He lifted his arms. "Lyfte ic þe in balwen ac forhienan se wideor!" A hot, desert wind suddenly surged through the valley, fanning the flames he'd created, and driving a burst of hot, dry air over Peg and through her. The water fell from her arms as the grass under her feet browned and withered, and so did the plants within twenty feet of where they were standing. And, for the first time, Peg actually looked pained by something he'd done. He strengthened the surge and she withdrew in on herself, holding her arms to her stomach, and moving back a step against the wind. Flames burst into being in different locations, crackling in the dry air. A single, dead tree in the verdant forest on the far side of them exploded with fire, and Merlin almost shook with the power of it.

When the wind slowed, leaving a nearly desert like world around them, she lifted her head and glared at him.

Then she smiled her terrible yellow-toothed grin, the expression garish in the flickering flames.

"You forgot one thing, warlock," she hissed, staring at him like she was about to eat him. "There is one other source of water, one you can't escape." She stepped towards him, and he suddenly felt his entire body going rigid.

"Over two-thirds of your body is water, and I'm going to pull it out of you." Her smile broadened. "Drop by drop."

He fought against it, tried to use his magic to shove her back, but even without touching him, she seemed to have a grip on him. Horribly, he realized that her mastery over her element might be greater than his over magic.

He could feel the flames he'd set already starting to die, and the wind he'd blown through the valley began to fade.

Out of the corner of his eye, he saw the dagger where it had fallen out of Gwaine's hand. With what was left of his strength, he lifted it up with his mind and threw it her.

It slammed into her side and she shrieked, and he felt her let him go. He staggered backwards, dizziness almost driving him to his knees, but he was clear-sighted enough to see her pull the dagger from her side.

And this time, the wound didn't immediately heal. In fact, it looked almost like it was bleeding. Dark green blood coursed out of the hole it had made, running down her leg. Throwing the dagger away, she stared at the wound, and then turned black eyes on him.

He had just enough time to build the flames back up before she raised her hand towards him. He called the broken sword to his hand that Gwaine had dropped and pointed it at her; hell, he'd set her on fire if he had to.

And then a percussive growl echoed through across the valley.

Merlin's eyes widened, and he looked to the trees. Peg looked as well, her gaze narrowing.

The ground rumbled with the force of their growls as the same three black dogs emerged from out of the burning woods, as huge as ever. Winding around the pockets of flames, the massive beasts stalked towards him like three black wraiths, and Merlin shifted to protect Gwaine from their advance.

Peg sneered. "Looks like someone didn't like you burning their valley."

He glared at her, and gathered all his magic inside him, letting the flames grow even higher along the river bank. He pulled his will together, ready to burn more.

"I have no fight with you," he called to the creatures. "But I have to stop her."

Ignoring him, the black dogs kept coming, walking right up to Merlin…only to suddenly turn and face Peg Powler, putting themselves between her and Merlin. Their growls deepened, knife sharp hair ruffed around their necks, teeth bared in full as they stared her down.

Her smile fell. "What is this? What are you doing?" she asked. "You are protecting a human?"

"We are protecting our valley," a different voice said, one Merlin recognized very well. The gray alpha padded coolly up to his side, her green, glowing eyes focused solely on Peg. Like a general surveying her troops, she sat down next to him and behind the three black dogs, and lifted her head. Even sitting, the gray dog was almost as high as his chest, which was beyond daunting.

"I have no quarrel with you," Peg snapped, backing up from the closest black dog. "Leave."

"You would poison all the rivers in this kingdom," the gray alpha hissed. "Those rivers feed more than just the humans."

"Then leave Mercia," she snapped. She threw a hand towards Merlin. "I'm sure Camelot would provide a wonderful new hunting ground for you. Kill him, and it will have no real protection."

The gray one lowered her head. "We will not be forced from our home by a grindylow," she said. "Especially not one as weak as you."

"Weak?" Peg scoffed. "You think I'm—"

"The warlock is powerful. I've never seen anyone take down an elemental so swiftly before. But he's rendered you nearly defenseless with just two spells and a dagger." She bared all her teeth, shiny and sharp. "You're vulnerable, Peg Powler. And, because of that, we can take you down."

Peg scowled. "Then you will all die." She lifted a hand, and one of the black dogs howled and went down—she was obviously using the same trick on it as she'd just used on Merlin a moment ago. Instantly, the other two attacked, teeth going for her throat and limbs. She shrieked, letting the first dog go, and punched, kicked, using her incredible strength to throw them off of her. But Merlin knew all too well how indestructible the black dogs were, and soon all three were fully into the fight, attacking her afresh as quickly as she could push them away or knock them down.

"Flames, warlock," the gray alpha warned. Merlin jumped slightly, and realized that his firewall preventing Peg from getting to the river had been diminishing without his attention. He nudged them with his mind, and the flames flared back up. Peg glanced at them and snarled, throwing one of the dogs through it, only to hear it land in the river on the far side. The same black dog leapt through the fire again second later, singed hair smoking mildly, and Peg quickly backed away from the firebreak.

Otherwise, Merlin stood where he was and didn't do anything. He didn't have to. Peg's defensive moves were getting weaker and weaker—he could see more of the dark green blood, and her skin was shifting from green to gray. Like watching a plant dry out.

She punched one of the black dogs, sending it flying, but the momentum staggered her close to the burning tree. Merlin broke off a flaming branch with his mind, and she screamed in obvious agony as it landed on her, setting part of her on fire. The dogs took immediate advantage, circling and snapping and tearing as she tried to get out from under them. She gave a mighty shove and ran forward, going once more for the river, but Merlin gestured and the flames along the riverbank simply grew higher.

"Whoa," Gwaine whispered, and Merlin looked behind him. He grinned when he saw Gwaine struggling up on his arms, blinking rapidly. Blood was caked on the side of his face, his black hair on that side matted down on a blood-covered ear. The knight was watching the fight between the black dogs and Peg, his lips parted in obvious wonder. "Where did they come from?"

"Apparently, they weren't too keen on the idea of Peg poisoning their river," Merlin said, quickly moving to kneel by his side. "You alright?"

"No," Gwaine admitted, still focused on the fight. He flinched, and Merlin looked towards the melee. He felt the bile rise up as he realized that one of the dogs had managed to rip one of Peg's arms off above the elbow, the limb instantly withering, until it looked like no more than a dead, dried out reed. She was shrieking constantly now, in pain, but she was still fighting tooth and nail, trying to stay alive.

Merlin turned his head away. He didn't want to watch anymore.

"Ow…" Gwaine said, obviously not suffering the same revulsion. "She just lost a lot of middle. Hell, she's nothing but mud and water in there…"

Merlin shuddered.

"And…there," Gwaine whispered. "It's…it's got her neck. She's done."

The shrieking stopped suddenly, and so did the sounds of fighting.

Afraid of what he would see, Merlin looked back again towards where they'd been, and saw the three black dogs backing away from what looked like a steaming puddle of water with a few sticks, seaweed and broken reeds in it. All three bowed their heads towards it, almost in respect, and then turned and padded away, melting back into the trees without looking back.

Merlin frowned in confusion.

"They're just leaving?" Gwaine asked softly.

"Peg Powler is no more," the alpha said, still sitting next to them. She looked at them both. "She is gone, and so should you be. You will find your horses at the base of a path a few hundred yards that way—it leads up out of this valley." She gestured with her head toward the valley wall, and then looked at them again. "Do not return."

Merlin nodded. Letting go of the fire in his mind, the flames along the riverbank and elsewhere around the meadow quickly died, and a cooler breeze blew through the valley. Getting his arm under Gwaine, he tried to pull him up onto his feet. It was like lifting a blacksmith's anvil—the man wasn't as broad as Percival, but all that muscle made him insanely heavy. Gwaine tried to help, but his injuries were such that it was clear he was barely holding on to consciousness. Merlin grunted, feeling all the tendons in his neck and arms straining to get Gwaine upright, and his ankle shifted painfully with the extra weight.

"Wow," Gwaine muttered once he was almost all the way up, one arm hanging heavily over Merlin's shoulder. "The dogs do this?"

"What?"

"Burn the valley?"

"Um," Merlin blushed. "Yeah."

"Good thing they didn't do that when we were down here."

Merlin said nothing to that, just levered Gwaine higher on his shoulder. Taking one last look at the now innocent looking pool of water, the liquid already being absorbed into the damp ground under it, he started pulling Gwaine away from the river's edge, leaving the gray dog still sitting there, watching them leave.

"Human!" she barked out when they were at the trees.

Merlin turned his head.

"We will still hold you to your promise," she said. "But…" Her head bowed respectfully. "Thank you."

He gave her a nod, smiled weakly, and resumed the painful walk to the horses.

TBC…

One monster down. One, and a whole lot of mercenaries, to go…

And for those who know the show well, you may recognize the spell he used to create the desert wind. It's the same one he used against the afanc in season 1. I just...souped it up a little since he no longer has to hide who he is.