Riggennaxxas is a huge white dragon that dwells to the north of the Walrus Freehold. He is very old for a white (at least 550 years) and although some humans think that white dragons are stupid, they are just slow learners - and Riggennaxxas has had plenty of experience and time to think things through.
Riggennaxxas does not often venture into human lands and when he does, it is usually at night, silently soaring above unsuspecting towns and farmsteads. He does not attack humans or demihumans if unprovoked, but will happily snatch cattle and horses from fields without stopping in flight - he doesn't care about the distinction between wild animals and livestock.
When Riggennaxxas has attacked settlements, it has been in retaliation for some perceived wrong, and he will angrily announce his reasons for attacking, leaving survivors to learn the lesson. He has twice attacked Walrus City because adventurers set off from there on expeditions to kill him and loot his lair. The authorities of Walrus City now strongly discourage further attempts - lesson learnt!
Riggennaxxas's lair is a series of huge icy caverns dug into a glacier, with room for him to take off and land through a hole in the roof of the main chamber. His "pets" are a pack of 6 polar bears that cannot get out of the caves so they rely on food from the dragon. Despite this confinement, they are very loyal to him.
He particularly prizes gems, and his lair had many precious and semi-precious gems embedded into frozen walls and ceilings - prizing them out of their icy setting without damage could be tricky. Riggennaxxas does not care much for ivory, but he is aware that other creatures, particularly humans, consider it almost as valuable as gold, so when he kills a mammoth or walrus for food, he carefully removes the tusks and puts them in a side-chamber of his lair. He has acquired a stockpile of about 120 tusks, each worth 500 gp.
As well as gems and tusks, Riggennaxxas has large amounts of silver and gold as befits a dragon of his standing.
Riggennaxxas can be negotiated with - even traded with, but as a proud and superior dragon he is a touchy customer who always wants to come out on top in a bargain. He has traded with a band of elves who set off from the Twilight Forest, selling them mammoth ivory and breathing on a magic weapon that required a white dragon's frosty breath to fulfil its enchantment. However, in return they had to slay a frost salamander that had encroached on Riggennaxxas' territory. Similarly, a band of marauding frost giants are now killing the mammoths and caribou the dragon normally feeds on - any adventurers who dealt with these (either at Riggennaxxas' request or on their own initiative) would be in a better position to negotiate.
Riggennaxxas does not directly rule over any creatures except the polar bears in his lair, but he knows about imposing his authority on nearby settlements and tribes when needed. This is true of several villages of elves in the northern Twilight Forest, and some bands of ogres who roam the Icemud Tundra. They will all leave him alone for the most part but if he asks anything or if they have a common enemy, they defer to him.