AN: I think someone's done something similar to this at some point, but what do we know about the parents of the Shitennou? Here's my take on one... Could be the start of Papa!verse.
Who? OC (Kunzite adjacent)
Papa Was a Rolling Stone
By trade, he is a simple man - a blacksmith from the middle eastern region of the great empire of the Gemini. He pays his tithes and taxes. He participates in town life. He celebrates the Feast of Elysion. He makes offerings to the Lady Selene. And yet, there are whispers. Something about him is not normal. His silver hair is considered too exotic. His eyes - grey of a late winter morning - are not seen in these parts. Older citizens make signs to ward off evil when they see him. When he was younger, his mother plastered mud in his head - trying to diminish the color, but since her passing, he has accepted the tone. Call it pride, but it is something that sets him apart.
When soldiers come from the capital and the town is asked to provide one man to serve, he sees the stares, understands the unspoken expectations and is in no way shocked when the mayor says, "Kohar will go."
There is no point in fighting what Lady Fate has decided for him. Kohar puts down his tools, wipes the sweat from his brow and says, "Let me collect my things."
They take the overland route by the coast and Kohar watches quietly. He has never left the village before and all that appears in front of him he commits to memory. The expanse of sea, the growing population - where has he been living his whole life? Along the way, they collect other tributes - men culled from various regions. All are wary, unsure what the service to the crown will entail. There are rumors - endless whispers of what awaits them in the court of the Gemini. Once in the city, they are forced into barracks and fierce training begins. Having made swords his entire life, Kohar excels and naturally rises through the ranks. Here, he is accepted. Here, he is important. People listen when he speaks. While he puts on a front of accepting orders at will, try as he might, he cannot get an answer of what they are preparing for.
Finally, in the middle of a moonless night - the answer comes.
In the court of the Gemini, two brothers are at odds. Behind the back of the other, one has wrested control of the military - loyalty to him alone. Dissenters from the schism will be executed.
Kohar has interacted with both men. The betrayal sickens him, but he pushes down the guilt and does as he is told.
The coup is bloodier than either side imagined. Many brave young men lose their lives. When the dust settles and the dead are buried, for his bravery in battle, Kohar is given a grand new title, King of the Middle East, a Shitennou. In a ceremony, a magnificent sword of his own design touches his shoulders and he rises a knight of the new realm - the reign of the Terran army has begun.
And yet, for his loyalty, Kohar felt he has betrayed his country. He is fearful, sleeping with one eye open, knowing there are still those loyal to the brother who lost. He remains vigilant until a fair maid catches his eye and his nights are spent in leisure. In turn, her abdomen grows round and he counts the days until his son will join them. In the days nearing the birth, he feels the need to return home - to make amends, to atone for his sins. She begs him not to go - that the town will be there after the birth of their child. He sets out before dawn, along the same road that brought him to the capital. Will they recognize him? Has any word of his exploits made it back to them? How will he be received?
The village is smaller than he remembers. It seems untouched from the ravages and bloodshed of the coup. Perhaps, he can bring his love here and spend his days ruling from an outpost - tucked away from the drama and backstabbing that court life seems to bring. The trademark silver hair, once shorn close, now streams in the wind like a banner. Tying his horse up, he is cornered by a man he's known his entire life.
"You betrayed us."
Kohar doesn't understand. How could this remote outpost be loyal to one brother or another? "How?"
"You left to support the court of the Gemini. Now we are Terran."
Another man approaches, "You know we don't take kindly to change."
What did he expect? Gratitude? He knew they were a simple people, but didn't realize how deep that ignorance went. And then he notices the town gathering around him. How had he let his guard down?
"Why did you return?"
"Think you're better than us, 'King?'"
"They said you would be back some time or another."
A sword appears, then a pike and a pitchfork.
Before long, the silver hair lays limp and bloodied.
And thus, Kunzite, son of Kohar, comes screaming into the world without a father. In a sense of commitment to the next generation, the new king appoints Kunzite the title and after a few years pass and the heir to the Terran king is born, the young Shitennou, a serious, quiet boy, swears allegiance and protection to the new prince.