Need a character background written up?

[Tawmis]

i need help expanded on a idea
Name: Jericho
Race: Tiefling
Class: Kensei monk( uses whips flavoured as chains)
Gender: Male
Background Marine
Rough idea: jericho was the first born child of a noble human family and , they kept him locked up because of his appearance and after a couple of years being lock up he escape and he trained to become a marine

The noble family with a Tiefling heir is always fun to explore!
I used that as a reason to explain why as a Monk you'd be well versed with chains (whips reflavored) and why and how you become a "Marine" (Warrior type).
As always, I appreciate an feedback you have!
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I spent most of my life in chains.

I was born to a noble family and by the age of five my bloodline made itself apparent. Long ago, it’s said that my mother’s side of the family had made a pact with a demon of some kind, in hopes of financial success. A part of that deal required laying with the demon, who planted the seed for his spawn to be born one day when he was needed. As a part of the deal, the child – when born – could not be killed. It’d been generations since that deal happened – but it was a secret passed down generation to generation on my mother’s side.

When I “disappeared” – my mother had lied to my father and explained, with their crocodile tears, how I’d had a tragic accident. My mother even arranged an elaborate funeral, keeping the casket closed, saying the body was too badly damaged for an open casket, and buried an empty coffin.

For ten years, I struggled and pulled at chains to try and break free as my parents sent their servants down to throw food in my direction – because my own mother could not bare the sight of me.

When I had finally turned fifteen, one of my mother’s servants – a woman named Pellina – took mercy upon me and freed me by smashing my chains at the connection. She led me through a series of servant tunnels that led to the outside, giving me a small bag with food and drink.

I fled into the woods in the middle of the night with only the moon watching me. I heard several days later that Pellina had tragic accident, undoubtedly one arranged by my mother.

For a week I followed a dirt road, traveling with a series of others, taking safety in numbers. When I arrived in Winterstone, I stayed here for weeks, living on the streets. That’s when an elderly man took notice of me and noticed the shackles still on my wrist. I’d broken the chains off weeks ago with the help of a blacksmith I met on the road.

“Are you without a home?” the elderly man asked, his arms folded behind his back.

“I am,” I replied, “but I am all right.”

“Your appearance,” he noted, “Tiefling. Demon blood. Is that why you are without a home?”

“Something like that,” I nodded.

“What is your name?” he asked.

“Jericho,” I replied. “The name I was given by my mother and father. But…”

“They are the ones who cast you out,” he shook his head, “so you do not feel like that is your name.”

“Yes,” I acknowledged.

“Well, come with me. My people will not judge you for your appearance. We will show you that what you look like does not determine what you will become.”

Because I had nowhere else to go, I accepted his offer. He took me to a monastery outside the edge of the town and I officially joined the Order of Winter – a band of Monks trained to fight and protect the world from evil.

As I trained, I first learned to use a whip – but quickly found – my years chained to a wall made me well versed in using chains as a weapon.

By the age of twenty, I was ready to be unleashed on the world and set things straight.

One day, I may even pay my dearest mother a visit…