(First two paragraphs taken from Cerin the Charmander's Background, used with permission)
Thirty five years ago, the Char-clan of Red-Talon ruled over the mountains with a blazing fist. They were ruthless, battle hardened warriors who only sought after increasing their own power and glory. Feared by most, despised by others. They thought themselves as the true rulers of the continent. By that point in time, they weren't just a powerful clan. They were an unstoppable army.
However, the other mountain clans feared Red-Talon's power, and what might happen if they decide to march on their land. Beneath the earth's crust, far below the watching eyes of any air-fairing Red-Talon, an alliance was formed. Several of the smaller rival clans joined their mightiest forces together, and soon, the rumors of an oncoming war spread across the land like wild fire. Had their plans gone into fruition, it only would have amounted in death of thousands of Pokemon on all fronts.
Uniting these clans and naming himself their leader, Olaf the Nidoking, was aiming to overthrow the tyrannical Red-Talons and establish his own reign over the mountains. Having been named Warlord of his own clan at the age of fifteen after the death of his father, it had been Olaf's life-long dream to bring wealth and power to his clan, whom he regarded as his family. Sensing the signs of an uprising, he siezed the opportunity to unite the underground clans and establish himself as their leader.
However, fearing the loss of life that would ensue if war did break out, the peace-loving Water Clans decided to erase the Red-Talons, sacrificing thousands to save millions. In addition to this, they also thought it wise to put an end to Olaf's reign, and thus prevent another Dictatorial ruler from assuming control of the mountains.
In the wake of this great purge, the great northern cities of the mountains sank into chaos, and many pokemon fled in search of a place where they could live their lives in peace. Hidden among the dozens of eggs taken with these caravans was the egg of Odyr (pronounced oh-dear), son of the late-warlord Olaf and his mate, a Torterra. She had given him away out of fear that he would live a life of ridicule in the mountains, or even be asassinated by the Water Clan to end his father's legacy.
And so Odyr was sent to the orphanage of the nearest town, Amaryllis Town, and was soon adopted Mystery Dungeon syndicate because of the potential he had shown during his first few weeks in the orphanage. He has been training ever since, unaware of his family's bloody history.
Odyr takes after his father in many aspects. He is a natural-born leader, strong and steadfast in his convictions, although they mostly involve the acquisition of loot, and he will do almost anything to lead his team to victory.