Brigznier

The Ancient copper dragon known as Brigznier, Has called the Underdark his domain for many hundreds of years. His shear size and strength have allowed him to prowl the Underdark un challenged for his whole life, For he has power that many citizens of the Underdark need, Fire.

His tainted flame condensed into green crystals and offered as trade for food and treasure.

With mastery over gravity Brigznier has learned to use it the create fair few things valued by others. His corrupted essence for one acts as a fuel and catalyst for many things in the Underdark, From simple lighting of Drow homes, to fuel for Illithid machines.
Making him an invaluable part of living in the Underdark.

Those that have tried to fell the obese beast have met their end, Crushed under his immense weight or simply devoured by the Dragon.

Brigznier appears as a very overweight black dragon. those more fine tuned may notice that Brigznier's scales have a metallic sheen, Confirming that Brigznier is actually a copper Dragon, A lifetime of greed and selfish behavior have darkened his scales considerably.
Greedy even by Dragon standards Brigznier has done little aside from gorge himself into long slumbers, Waking again to gorgore further. Only interacting with the Underdark when his food supplies are low or his hoard's collection becomes stale.

He is very self absorbed, Those around him are merely entertainment for the day to day. even when other Dragons have come to claim his treasure Brigznier has defeated and devoured them.
He has an unlikely working relationship with the Duergar of the Underdark. They happen to have quite a bit of raw gold and gemstones with little use for them but a Dragon's fire can be used to light their forges and provide warmth. Almost weekly the Duergar trade their mined wealth for the Dragon's condensed flame.
Recently The Dragon has made simple communication with the few Illithids nearby and even a Beholder. Talks are slow as the parties have little in common but progress is being made.

His weight has overwhelmed his body, Unable to fly and struggles to walk. Despite this his presence is no less intimidating. Being far more gargantuan then any other Dragon. Even without the excess weight, Brigznier would be close to twice the size of a Ancient gold Dragon. Its unknown what exactly promoted this excessive growth. it could be a side effect of his gluttony or perhaps an effect of the Underdark.

The Dragon spends his time in the lower levels of the Underdark. Slumbering within his massive hoard of treasure.

Brigznier is quite the chatter and is eager to swap stories with strangers. He will often even trade treasure for a good story.

The Magic items in his hoard all have curses of them due to their proximity to the dragon.

Brigznier is quite the active love maker, Especially before his gained weight ruined his figure. Its possible there are few children of his heritage that he doesn't know about.

Every few decades Brigznier starts the long process of moving his hoard to a new location.

Despite spending his whole life in the Underdark his eyesight and flesh still cope with the sunlight normally due to his lair being nearby sources of lava.

Becoming a Smith
In recent years Brigznier has come into contact with a Stone giant by the name of Gavlain. Though Giant's and Dragons are known to be mortal enemies for many millennia the two seemed less than eager to start a grudge match. instead they swapped stories for well over a few weeks.

Gavlain taught Brigznier how to smith. Giant's Craft. Unique brand of smiting of folding lightning like hot metal Normally a closely guarded secret of the Storm Giants.
Harnessing the raw power of unique ore found in the Underdark, Brigznier is now able to forge weapons made of pure green lightning.

Created, Recruited or released by the New gods of this world. They promised you Freedom, Riches or maybe purpose if you succeeded on the task they needed done.

Accepted you carried out your duty but something was a miss, The Gods didn't hold up their end of the bargain. The task was impossible to complete or perhaps even desecrater you beyond what you used to be.
Not only are you left betrayed by the very gods but you are now trapped in what ever situation you were tasked to do.