"There is no law against a shikigami challenging a shinigami," Rikugo said softly, watching Byakko's tail twitch in anxiety. "Tsuzuki is a trespasser and as the lord of this realm, Sohryu is in his right to call him out."
"But it's not a real challenge! This isn't about Tsuzuki getting another shikigami!"
"No, it isn't," the astrologer agreed. "This is about Sohryu's hatred of him and his need to prove that he's right about Tsuzuki, that he his weak."
Byakko snorted. "He'll be in for a surprise."
Rikugo nodded. Underestimating Tsuzuki Asato was a dangerous and easily done thing. He had never allowed himself to do just that, but he also hadn't believed him capable of defeating him in a battle of the minds. Even under spiritual pressure, Tsuzuki had prevailed. He was an amazing individual, someone Rikugo served gladly.
Byakko's tail twitched again, relaying his nervousness and agitation. Neither he nor the others were allowed to help Tsuzuki – just like throughout a normal challenge -- but there would be no third party judging the fight. This wasn't a challenge issued by a shinigami seeking a servant. This was a shikigami who had seen an intruder in Tsuzuki. That he hated the other man was secondary at the moment, but it would play into the fight as well.
It was sheer luck that Suzaku wasn't here at the moment. The Phoenix would have given Sohryu hell, would have tried to protect Tsuzuki. They all wanted nothing more than to keep him from harm.
"There will be no mediator," Byakko murmured. "I really hate this."
Rikugo said nothing, just nodded thoughtfully. No mediator meant that everything would be allowed. Sohryu was old and powerful, and he was sneaky.
A small niggle of worry started, blossoming into fear.
He would hate seeing Tsuzuki get hurt; or worse.
"Let's go," he only said.
Watchers were allowed and he and Byakko would do just that. Watch and hope and maybe pray.

Tsuzuki met the cool, dark gaze levelly, aware of the danger this man represented. He hadn't wanted the challenge, he hadn't planned on gaining a new shikigami. He had four already, of which one had been more or less an accidental claim, and that were more than he had ever hoped to have.
That Sohryu had seen his presence within the boundaries of his realm as a challenge was a realistic scenario, but none of the other shikigami had ever called him out because he was simply there. Usually shikigami were hospitable, friendly and warm beings; those who didn't like humans or contact to others simply withdrew into the far regions of GensouKai. Sohryu had done no such thing. He openly distrusted humans and he had often stated how much he despised Tsuzuki's claim on three Gods, the three of the four elements, and one additional shikigami in form of Rikugo, who was a formidable adversary all on his own.
Oh well, it can't be helped, he thought tiredly. It wasn't a physical exhaustion, just the fact that he didn't really want to fight the water dragon.
Sohryu was an impressive man. Tall, slender, dressed in rich, multi-layered robes, he stood tall and proud. The long, dark blue hair was intricately decorated just like the clothing, and his chiseled features held the haughty expression of the noble dragon he was. There was a look of disdain in the cold eyes as he let his gaze roam over Tsuzuki's form. He knew what it looked like to any outsider. He, dressed in his usual suit with its tie askew, hair tousled, looking so very harmless, and Sohryu, the Protector of the East, the powerful lord of this realm. Two very mismatched fighters indeed.
Byakko was fretting at the outside lines of the assigned battle field. The tiger had hovered around him all day, nervous, anxious and close to stepping in for his master and going at Sohryu himself.
"It'll be fine," Tsuzuki had calmed his friend again and again.
"If you lose you'll die!" Byakko had repeated what he had said over and over before.
"I know the rules of the challenge."
And if Sohryu lost he would become his shikigami.
"Tsuzuki…!"
He had hugged the tiger then, felt strong arms come around him, had felt the shuddering breath against his skin. Byakko was scared for him. It touched him, it frightened him… and it warmed him.
"I don't want to lose you," the wind shikigami had whispered in a very small voice.
"It'll be all right, Byakko," he had answered, touched by the emotions.
And now he was here, facing the one shikigami he would never have challenged, who didn't like him, and who was now out to kill him.
Tsuzuki inhaled deeply, calming himself, reaching for his power. He felt it curl around his touch, a quiet reassurance. He didn't want to use it, but as a last resort he might have to. He hated the darkness, the inhuman ability he had, even though as a shinigami he was a magic-user. But this wasn't pure shinigami magic. Pushing those thoughts aside, he concentrated on the challenge.
Sohryu's cold smile was his only warning before the dragon changed into his second form and attacked.
The challenge was on.

Sohryu stared at the slender shinigami still standing there, hard eyes locked on his, face a mask of determination. Blood was flowing from several open wounds, pooling on the ground. One hand was clearly crushed from that last attack. Sohryu had triumphantly clamped down on the fallen angel, sure in his victory and that he only had to crush him with his paws. What he hadn't believed in was the very possibility that Tsuzuki might strike at him once more. But he had. An incredible energy force had thrown him clear off his prey, smashing him into a mountain face, stunning him.
There was a deep wound in Tsuzuki's right thigh from that attack as well, blood staining the pants, glistening wetly, but he was standing, unbroken. Power radiated from him. An immense power. The power that had nearly taken Sohryu apart.
The dragon himself was bleeding from numerous wounds, he felt his own pain and exhaustion.
By the Gods…
Who was that man?
Sohryu exhaled softly, his body shaking from stress and his dragon eyes were still fixed on the small human being.
He had been beaten.
By a mere human. A child in his eyes.
… a shinigami who had three of the four Gods already under his command and had now conquered the fourth.
He had a master now.
He had… a master.
The thought settled in. Slowly.
He had never had a master before. He had never been challenged. Gods weren't challenged.
"It's over!" Rikugo announced, now entering the battle field, all eyes open and fixed on Sohryu, who couldn't react, who could only stare at Tsuzuki.
Beaten…
Mastered…
The Azure Dragon of the East.
Sohryu wasn't even aware that he was turning back. His point of view changed, but his view didn't. Clothes were torn and singed, blood stained the expensive robes, and his elaborate hair style was… non-existent. He felt the sword at his side, but it was just a piece of metal now. Like Sohryu himself it had been conquered.
Tsuzuki was still holding his gaze, eyes hard, unyielding.
He was so incredibly powerful… This small human, this worm...
Non-human eyes followed the blood running down the pale, determined face, watched the drops spatter on the ground. He had hurt him. Badly. Still, he was standing. Probably unable to defend himself, but Tsuzuki had already won him. Part of him wanted to attack once more, to tear this man apart, while another just stood in amazement, touching the invisible lines of power radiating from this plain human.
Byakko, who had watched from the sidelines, carefully walked up to them.
A shudder ran through Tsuzuki and Sohryu could see how the badly injured form was starting to sway. Still, the eyes held his, sharp and cold. Power flickered. His eyes narrowed.
It was as if Tsuzuki was bringing a point across. The dragon wasn't facing the man he had challenged. This was a different Tsuzuki. Those eyes…
I won, they seemed to say. And I'm ready to continue should you choose to do so. I can beat you again.
How could he? How could he even think of moving a muscle?
Blood continued dripping, leaving the frail body, but the shinigami was untouched by his growing weakness.
Who are you? Sohryu thought, stunned beyond words.
"Tsuzuki?" Byakko tried carefully.
Another shudder and Sohryu heard a rattle of air leave the abused lungs.
Why was he still standing? How could he in the condition he was in? Sohryu was baffled, confused and totally stunned.
Byakko was now next to his master, red eyes filled with worry, and he reached out to touch one bloody shoulder.
"It's over," the tiger said softly.
The inhuman eyes left Sohryu's face for the first time. Lips moved, but Sohryu's hearing picked up no sound. Still, Byakko nodded.
The pale face changed dramatically from the mask of determination to one of incredible pain, and then Tsuzuki collapsed. Amethyst eyes rolled back in his head, the last drops of color left the already chalky white face, and he simply fell to the ground. Byakko gave a cry of alarm and caught him, lowering him to the ground. Sohryu snorted in disgust. What a shameful picture. The Protector of the West, a God, on his knees next to this pathetic creature.
This pathetic creature beat you, a voice reminded him.
Him, the Protector of the East, the leader of their world.
And why was there a niggle of worry? Why was part of him trying to make him move over there, see what was happening, how badly Tsuzuki had been injured?
He remained where he was, staring at the scene unfolding now. Rikugo had joined the anxious tiger, calming him, talking in a soft, reassuring voice, and then did the unthinkable. He picked up the limp, bloody form, uncaring of his clothes that were now just as stained as Byakko's, and walked away, the tiger in tow.
Sohryu didn't move.
Shock kept him rooted to the spot.
He had been beaten.