The "Heart-Poison Mark" originated from the Western Regions, from a kingdom called Vatuma that rose after the fall of the ancient Garuda Empire.
This was the greatest nation in the West, home to the most accomplished group of Gu Masters in existence.
Since ancient times, poisons and Gu had always been inseparable, and those who practiced Gu arts were inevitably experts in the use of poison.
The "Heart-Poison Mark" lay somewhere between poison and Gu, acknowledged as the world's foremost, unsolvable venom.
Of course, this ranking was somewhat controversial.
After all, there were at least five other poisons in the world equally without cure.
And since none of these poisons could be resolved, and no one had ever dared test them one by one to see exactly what level of cultivator each could kill, who could truly say which was superior to which?
It was only that, from the ancient Zhou era to the present day, the "Heart-Poison Mark" had the most impressive record of lethality.
Because this poison had once killed an emperor of ancient Zhou.
An emperor, bolstered by the fortune of a nation, even if lacking personal cultivation, was considered at least equivalent to a third-grade cultivator.
Thus, the "Heart-Poison Mark" was ranked number one on the known list of toxic powers.
However, the term "unsolvable" here referred only to the limits of orthodox medicine and alchemy, not to every conceivable method.
For instance, if Gu Fangchen could find a cultivator from the Tara Sect of third grade or above willing to sacrifice themselves voluntarily and transfer the poison onto their own body,
then never mind one "Heart-Poison Mark", even ten or eight of them would no longer matter.
Unfortunately, the Tara Sect was unlikely to offer him such a favor so easily.
As for the "Path of Mercy," the school once renowned throughout the land for its medical and alchemical arts, it had been lost since the fall of ancient Zhou. Only fragments of its medical texts and pill recipes remained scattered across the world, half-understood by later generations.
By the time of Great Wei, the status of medicine and alchemy had declined drastically, largely supplanted by the Tara Sect.
After all, no matter what part of the body felt unwell, one simply had a Tara Sect adept transfer the ailment away, problem solved.
In a sense, this was precisely why the "Path of Mercy" had remained lost to this day.
The "Heart-Poison Mark" on Gu Fangchen's body parasitized his heart, rooting itself there. From that base, it drew nourishment from the veins throughout his body to sustain itself.
When it had absorbed enough vitality, it would "sprout" from the heart, blooming into a gorgeously demonic crimson flower.
That was the blood-red pattern that wound from Gu Fangchen's right hand all the way to his heart.
When the poison matured, it would corrode its host from within, turning flesh and blood into a pool of gore, which the flower would then drain dry, leaving behind only a shriveled human husk.
The "Heart-Poison Mark" was said to lie between Gu and poison precisely because, while releasing toxins, it was also a living organism, though one that could not move on its own.
What made it truly terrifying was that it fused instantaneously with its host's heart, replacing its function entirely and becoming part of the human body itself.
If the victim's cultivation was weak, there was no way to remove it before it consumed the heart.
A plant cannot live without a heartwood, and a man without a heart, certain death.
Much more so when the victim had been a child, as Gu Fangchen was at the time.
Even worse, the "Heart-Poison Mark" did not merely feed on flesh; given enough time, it could also parasitize the soul.
Even if the soul were to leave the body, it would still cling to it, draining both flesh and spirit dry.
Its horror was beyond imagination.
In this sense, the poison was already close to a secret art of karmic causality.
When Gu Fangchen had first been afflicted, the royal house had invited Master Juehui of Garan Temple to seal it using the Buddhist technique Flower-Grasping, preventing the "Heart-Poison Mark" from further growth.
To seal it, a drop of Gu Fangchen's heart blood and a wisp of his soul essence were required.
These two things had ever since been placed beneath a wrathful Vajra statue in Garan Temple, suppressed by pure and unyielding Buddhist radiance.
And that was precisely why Gu Yuye had summoned Master Juehui now.
The heart blood and soul essence had remained there untouched all these years, unstained by any external karma, and thus impervious to any interference from that wretched brat's karmic secret arts.
With the heart blood, one could verify whether this body truly belonged to Gu Fangchen, and by extension, whether he was truly Gu Yuye's son.
With the soul essence, one could further confirm whether the soul within this shell was indeed Gu Fangchen's-
or some other ancient monster that had seized his body.
Gu Yuye drew a deep breath and was about to leave when he was stopped by Xiao Qiu, who came hurrying from within the hall.
"My lord, please wait."
Xiao Qiu's round, genial face wore a courteous smile as he bowed respectfully.
"His Majesty requests your presence in the Purple Extremity Hall."
Gu Yuye turned his gaze toward the towering hall.
"Hasn't the matter of Autumn Peace Road already concluded?"
Xiao Qiu flicked his horsetail whisk, stepping aside slightly as he replied calmly,
"The Crown Prince has just reported to His Majesty that the Seven Sects of the Southwestern Four Prefectures have secretly joined forces. They have already annexed three prefectures and may be preparing to revolt..."
...
Xiao Sheng slowly entered the Purple Extremity Hall and knelt tremblingly.
"Your son greets Your Majesty..."
"Rise," said Emperor Yong'an gently. "I've told you many times, you are old; you needn't kneel every time. Between father and son, why cling to such formality?"
The emperor's words were soft with concern, yet for Xiao Sheng, they carried the cruelest truth of all.
The Crown Prince lowered his head, his face blank.
From the polished black floor of the Purple Extremity Hall, he could see his own aged, decaying reflection.
How absurd, that a father could tell his son, you are old.
More absurd still, that he had held the title of Crown Prince for a hundred and fifty years.
From birth, Xiao Sheng had been the rightful heir, born of the Empress, the legitimate first son.
Who could have been more suited to the throne than he?
From childhood, he had carried that belief with clarity and diligence, striving to become a virtuous ruler.
He had devoted himself to governance, studied the classics, and was praised by his tutors as a man of ancient benevolence, destined to bring grace to the world.
At thirty, Xiao Sheng had believed this wholeheartedly.
But Emperor Yong'an remained strong and tireless, ruling a stable realm, far from any thought of abdication.
Back then, Xiao Sheng had not realized the gravity of that situation. The emperor treated him strictly as an heir and even allowed him to assist in governing.
He had thought that when his father grew weary, the reins of power would naturally pass to him.
No one could have imagined that he would wait more than a century.
Until his hair had grayed and his vigor withered.
Until the bright flame of youth faded alongside his teeth and hair.
"Yes."
Xiao Sheng responded softly and, aided by the attendants, stood and took the seat prepared beside him.
Emperor Yong'an tapped the armrest of the dragon throne with his fingers.
"You came in such haste, is it about the investigation from the other day?"
Xiao Sheng coughed twice, then nodded and bowed.
"Your Majesty, the Seven Sects of the Southwestern Four Prefectures have indeed made covert moves. They appear to be uniting, seemingly with the intent to encircle Sword Pavilion."
Emperor Yong'an said calmly,
"When Sword Pavilion suffered its internal strife years ago, these sects were already involved. But they were all repelled by Ning Songjun. Are they now seeking to return?"
"It appears to be more than that..."
"Oh? Speak."
Xiao Sheng's tone deepened.
"According to what I have learned, there are rumors spreading throughout the Southwestern Prefectures that within Donglong County's Donglong Lake, where Sword Pavilion stands, there lies another divine-grade sword, apart from the one resting on Heaven's Gate Mountain."
Emperor Yong'an's interest sharpened.
"Another divine-grade sword?"
Xiao Sheng nodded.
"It is said that this sword was forged by a traitor of Sword Pavilion, a demonic blade that once brought calamity upon the mortal world during ancient Zhou. Later, an immortal seized it and cast it into Donglong Lake, using the dragon vein beneath to suppress its baleful aura."
At this, Emperor Yong'an's eyes glinted with amusement.
"A dragon vein?"
Then, after a brief pause, his expression hardened, and he slammed the armrest.
"Impudence!"
At once, every attendant in the Purple Extremity Hall dropped to their knees with a rustle.
Xiao Sheng immediately stood, then knelt as well.
"Your Majesty, calm your anger!"
Emperor Yong'an said coldly,
"Continue."
Xiao Sheng kept his head low.
"The dragon vein is the very root of national fortune. Though the Seven Sects claim to be vying for the sword, who can say they do not covet the vein itself?
If the legends are true, and that demonic sword must be suppressed by the dragon vein, any disturbance might harm it.
Should the vein be damaged, the empire's fortune would waver, the consequences would be disastrous.
Therefore, your son hastened here to beg Your Majesty's decision on how to quell this coming unrest among the Seven Sects."
He had come to seek imperial counsel because, on the surface, this was a matter between cultivation sects, not a worldly rebellion.
The imperial court and the immortal sects stood parallel, not in authority over one another.
Except for the Confucian schools, which were fully integrated into the state, the court had no standing to command any sect.
At most, it could send envoys to mediate.
Yet for the court to intervene in a conflict involving seven sects across four prefectures would seem an overreach.
Emperor Yong'an pondered a moment, then sighed softly, rubbing his brow.
"Summon Gu Yuye."
Xiao Qiu quickly departed and soon returned with Gu Yuye, who had not gone far.
"Minister Gu has arrived."
Emperor Yong'an asked,
"Has Xiao Qiu explained the matter to you?"
Gu Yuye nodded solemnly.
"I am aware, Your Majesty. But I do not yet know why you have summoned me here."
He was, after all, the "Saint of War." Could the emperor possibly intend him to march an army against the Seven Sects?
How would the other sects take that?
Given their arrogance, most already despised imperial interference. If he did so, it would ignite chaos.
Even a reckless emperor would not do such a thing,
and Yong'an was anything but reckless.
Moreover, Gu Yuye had only just been reprimanded by the emperor. For him to be employed now was not in Yong'an's usual manner.
At the dais, the emperor suddenly stood, lifted the heavy curtain before him, and stepped down to face the two men below.
He appeared no older than thirty or forty, his face youthful, his bearing unpredictable, moods shifting like shadow and light.
Then, spreading his arms before joining them again, he clapped lightly and smiled.
"Minister Gu, I have just thought of a most excellent solution, one that can resolve both the Seven Sect unrest and your... family dilemma."
Gu Yuye froze.
Emperor Yong'an continued with a smile,
"Your heir, the Shizi, has just returned to Sword Pavilion with the Princess Consort, has he not?"
Gu Yuye's pupils contracted sharply.
"That is indeed what I was told, but as of now, they have not yet, "
Yong'an's tone grew softer, but his smile remained.
"In that case, let our top scholar accompany them."
He chuckled faintly.
"You cannot tell which son is truly yours, then let me help you decide."
"Since ancient times, the position of heir belongs to the capable. Whoever quells the Seven Sect unrest shall be the Shizi. What say you, Minister Gu?"
Countless thoughts flashed through Gu Yuye's mind.
But at this moment, refusal was impossible.
Besides, this arrangement might actually serve him well...
In terms of talent, how could Gu Fangchen possibly match Gu Yuandao, the son he had personally trained?
Gu Yuye bowed deeply.
"Your Majesty is wise."
...
Ning Songjun's expression was one of utter disbelief.
That man, he was a Martial Saint!
Decades ago, who hadn't heard of the Martial Saint's name? And even though Ding Xingfeng's reputation had later plummeted because of that fateful dictum, his achievements were real and beyond question.
Countless people still revered him.
Even Ning Songjun himself, though titled the Sword Saint, had grown up hearing tales of the Martial Saint, an idol to an entire generation.
Moreover, Ning Wuzhen and Ding Xingfeng had shared some acquaintance.
Though Ning Songjun bore the title of "Sword Saint," in his own heart, he still saw himself as the younger generation before Ding Xingfeng,
and harbored genuine admiration.
But never could he have imagined that when Ding Xingfeng finally reemerged, he would take his useless nephew as a disciple!
Ning Songjun was silent for a long time before saying,
"If he is merely a registered disciple, then perhaps..."
Ning Caiyong quickly corrected him.
"He is a direct disciple!"
She was immensely proud of that fact, so much so that even her own younger brother was not permitted to mistake it.
Ning Songjun: "..."
A direct disciple?
He turned toward Gu Fangchen, his eyelid twitching.
He had watched this boy grow up. How on earth could he become the Martial Saint's personal heir?
If anyone deserved it, it should have been Gu Lianqian!
Surely there must have been a mistake.
Gu Fangchen said earnestly,
"As the saying goes, 'A gentleman should be judged anew after three days.' Uncle, it's been at least three years since you last saw me, hasn't it?"
"So it's perfectly reasonable that I've advanced to the sixth grade."
No, it was not reasonable at all!
Ning Songjun's face remained expressionless, though inwardly he felt he might be the only sane man left.
He pressed his fingers to his forehead.
"Hold on, how exactly are you able to cultivate?"
Gu Fangchen shook his head, glanced at the old man beside him, and said righteously,
"Master said, no comment."
"But the 'Heart-Poison Mark' is still on me, Uncle. You can see for yourself."
He calmly extended his hand.
Upon his right palm, that twisted, demonic blood-red pattern was clearly visible.
Ning Songjun froze.
Indeed, he had been too preoccupied with Ning Caiyong's safety earlier to closely inspect Gu Fangchen's condition.
Now, with a single thought, he sensed it clearly, the "Heart-Poison Mark" was still present, dormant within Gu Fangchen's body.
No one in their right mind would take such a poison upon themselves just to impersonate Gu Fangchen.
Even a second-grade cultivator would never dare.
At last, Ning Songjun's tense nerves began to ease.