(In my head narrative I tacked on a whole new region for my house to Lord Paramount of haha, I'll scale it down)
House: Vance of The Mountainlair (It's just too cool to me that my actual name is a Greathouse)
Sigil: A silver-and-black Shadowcat on a Chevron'd field of green, black and white
Colors: Green, Black and White.
Keep: The Mountainlair.
Ancestral Weapon: Valyrian steel single-handed longsword named "The Problem Solver" (reserve right to change questionable name)
Blood: Andal (though more First Men than most non-northern peoples)
Kingdom: Vale (though has strong ties to the Riverlands through proximity and blood)
Appearance/Traits: Broad and muscular but of average height with green eyes. Handsome enough not to be ugly. Slow to anger but act quickly when roused from the Mountainlair. Book learning is supported.
Founder: Willum the Wise
Origin: 500 years before the Conquest (or close enough as not to matter), Willum Vance came to age as the eldest nephew of the Lord of Wayfarer's Rest. With no particular inheritance coming his way, Willum looked beyond Westeros for a fortune and convinced his aging father to let Willum purchase a ship. Make no mistake - Willum hated sailing. He hated the smell, he hated the grime, he hated the motion and was no stranger to puking over the side of the ship. But Willum DID want adventure, so he took to sea on the Constellation.
And so Willum and the Contellation loaded up with what tradable goods he had and took to sea, departing from White Harbor. From there he sailed to Braavos and south down the far side of the Narrow Sea. Then it was east to Volantis and around the Freehold, past Qarth to the great island of Leng. By then, Willum's shrewd business had added several ships full trade goods to what became his fleet.
Willum of course dealt in gold and silver, spices and silk - but what Willum wanted the most was books. History books, geography books, books of ancient lore - it if was written down, Willum was willing to buy it. Years later, the Lord of the Mountainlair would jest that he would have returned home with an extra ship or two if it wasn't for the chests of books. On calm days at sea Willum could often be found below deck reading (it made him sick to read on more active ocean).
Willum had resolved to travel the make the rounds on the Jade Sea, but his plans changed at Qarth when he heard of upheval in Yi Ti. From there he sailed south and mapped a great swath of the west coast of Sothyros, discovering 4 rivers before turning back North.
Near the north-west tip of Sothyros, Willum led a group of men to investigate a crashed trading vessel. While inside the cracked hull, Willum and his men were set upon by a group of pirates who were investigating as well. Willum, a competent but not extraordinary swordsman, was disarmed by their captain. Willum stumbled back and spotted a hilt sticking up from the belt of a dead trader. As the captain lunged, Willum grabbed the hilt, drew the sword and ran the captain through. It wasn't until he was back on the Constellation that he noticed the tell-tale ripple of his new Valyrian sword, which he named "The Problem Solver."
After this latest near-death experience, Willum longed for dry land. His fleet sailed for Tall Trees Town, stopping just long enough to take on provisions and generate some more coin before headed back to the Sunset Kingdoms.
Willum's first act upon returning to Westeros was to sell all his ships except the Constellation (out of affection for the ship). After 5 years at sea, Willum took tome with his family at Wayfarer's Rest before embarking on his new obsession - lands of his own and a great keep inspired by ancient techniques from the Bone Mountains - The Mountainlair.
Willum cut a deal with Lord Arryn to purchase a tract of land along the western edge of the Mountains of the Moon. Willum selected a singular, tall, round mountain and hired engineers and artisans to build his seat. First, the mountain was completely stripped of trees and undergrowth. Then the dirt was removed, first with shovels and then with water pumped to the summit. Then, stonemasons leveled the top of the mountain off, leaving a flat stone plateau several acres wide. Then, stone was hewn away from the sides, more and more until they became sheer cliffs with one spiraling path upwards. The stone hewn from the top and sides was then fashioned into a keep at the top. It took 30 years and nearly all of his wealth, but finally, Willum had his seat, the Mountainlair, its stone pedestal rising several hundred feet above the valley below. The pedestal of grey stone was shot through with jet-black veins of coal.
In Recent Years:
The Mountainlair now has a modest town at it's foot and has grown to a mid-level player in the Vale (not a Royce or Corbray, but respected). Many Vances of the Mountainlair have become maesters. The Mountainlairs vast library is among the largest in Westeros and attracts the interest of many in search of wisdom.
When Lord Jon Arryn called his banners to support Lord Robert Baratheon's rebellion, the Vances of the Mountainlair were eager to join. Vance forces helped subdue house Grafton, with Lord Lysander Vance fighting side-by-side with Lord Baratheon as entered the town. Knights of the Mountainlair then joined Lord Stark's mighty host as it moved south. Once King, Robert rewarded Lord Lysander for his support with additional land.
During the War of 5 Kings, The Lord of the Mountainlair bucked the pacifism of House Arryn and chose to throw in with the other Houses Vance, sending 500 men with the Young Wolf. Only a few dozen returned from the campaign. As of now, Lannister loyalists are laying an ineffective siege on the Mountainlair. Storehouses and cisterns built deep into the stone pedestal mean life has gone on for the residents of the Mountainlair.
That was fun.