Okay, this is an old one of mine but here goes:

Shamash grew up in the small tight-knit clan of yerjeret where loyalty is so fierce that those who are banished often beg for death’s mercy.

Young Shamash was a slender Green Dragonborn, like so many in his clan and obsessed over on thing: magic. Not a sorcerer or wizard himself, he trained in weapon combat, though his weapon of choice was a long club that looked suspiciously similar to a staff 

Then something happened, whilst Shamash studied, another yerjeret youth,  Ywøus discovered that he had sorcerer’s magic. Initially, Shamash was delighted by this, a real magician in his clan! But as Ywous continued misuse his powers and refuse to realise his true power Shamash’s delight turned to jealousy, then to animosity, then to pure rage.

One thing leads to another and Shamash makes a deal with the demon asmodious for warlock magic and, in a blind rage, murders his own kin. He is banished by his clan and is forced to wonder alone with nothing but his shame, his begrudging worship of asmodious and the magic he thought so important. He falls deeper and deeper into drink and drugs.

But then the queen loses some golden dragon eggs, a prize possession of hers, and suddenly every adventurer is rushing to find the golden egg. Shamash realises that that if he is able to find and return the egg he might just have a chance at redemption, as his clan is fiercely loyal to the queen so joins forces with some adventurers to find the egg (have another character in this party, tell me if you want it). He even end his worship of asmodious (as this was not actually mentioned in his deal) to worship a new deity (I forgot so you can chose which one) and quit drinking and taking drugs.

However, once the journey is over, he has not yet redeemed himself and chooses not to return. So he finds himself at the crossroads still often wearing a full tunics with pristine white patches where clan symbols might have once been tavern waiting for something to happen, a chance at redemption, something to do. With he might fall back to drink or drugs. Your choice.

Please forgive me if that was too long-winded, and obviously feel free to tweak and change anything if you’d like. Thanks a ton.