Back To The 80s: President's Doted Wife - Chapter 14 - When Will You Endure

Due to an unexpected turn of events, Xia Fei consumed a Super Gene Optimization Fluid that bore no brand, expiry date, instructions or stated its place of origin.
Our story begins here…

He rose from abjection and achieved eternity in glory.
He embraced the prettiest beauties and killed the strongest opponents.
He was able to shift the clouds into rain and cover the sky with one hand.
He could overrun the entire world and go anywhere as he pleased.
He pacified wars and held the world in awe.
He was matchless in the world.
However, his hair turned white overnight for his beloved woman and he was on the verge of death.
He was surrounded by enemies who were trying to take his life.
He struggled his way to become mighty and fought for everything he cherished.
For this age, he was the only king of the Dark World.
His name was a byword for might.
As a man living in the world, his only ideal was to pursue brilliance.

- Description from Novelupdates

In a galaxy ruled by warlords, guilds, and ancient tech cults, Kai Zareth is just another debt-ridden scavenger—until a legendary system descends upon him.“One Trader per 10,000 light years. One chance to rise.”Selected by the Cosmic Trade Nexus, Kai becomes the sole wielder of the Galactic Exchange System, a multidimensional platform that allows him to buy and sell across parallel worlds, forgotten realms, and alien civilizations.With only 12 hours to complete his first trade—or lose everything—Kai scrambles to make deals in a universe where information is power and one wrong barter could cost your life.From selling enchanted goblin toothbrushes in toxic slums to outwitting rival system users and forging alliances with forgotten races, Kai must build his empire item by item, realm by realm.But in a galaxy where traders kill for profit and system users are hunted like prey, being the Merchant Sovereign might be a bigger curse than a blessing.

What is my 1000-year-old monster self to do when I’ve failed my immortal ascension? Time travel — accidentally — and wind up back in my 9-year-old body, needing to re-cultivate, of course. But after that? Get REVENGE! Muahahahaha! But the idiot who killed me — also accidentally — was the main character of the dumb harem Xianxia I transmigrated into. But wait. Wasn’t he only 7 or 8 at this point in time? Well, since I can’t harm a child or the main character without suffering in some way, then I’ll just have to raise him better, faster, stronger, and loyal! Muahahahaha!