Danchilaer
If the chosen person succeeds, Danchilaer somehow magically augments their personal abilities permanently and returns them from whence they came, charging them with a long-term goal or mission. Whether they follow his guidance or not, the Mad Mage haunts their lives, appearing in dreams to give cryptic advice or answering when they call on him in great need with a spell, spoken message, or helpful advice whispered in their minds.
Danchilaer appears as a tall, deep-voiced man in plain robes, whose face is always hidden by his pulled-down cowl. He's amoral, but neither insane nor malicious. His true aims are unknown, but the tasks and goals he sets seem dedicated to the survival of Dapplegate, the Border Kingdoms (as a region of free, everchanging realms, subject to no outside rule), and self-sufficient farming folk everywhere. He works against large armies, proud kings, and vast empires. Those who serve him are free to pursue their own lives and don't necessarily know of others the Mad Mage has "augmented." (Danchilaer is not building an organized group of agents.)
Yet several successful adventurers and mages now contemplating retirement to the Border Kingdoms have begun to meet for drinks and converse at various taverns about the Border lands in a sort of unnamed, unofficial social club -- and more than once, certain members of this group have acted together to foil petty rulers or stop unscrupulous mercenaries or merchants. Only the years ahead will tell if the Mad Mage has some larger plan or intends to forge those he has aided into some sort of cohesive force. If he does, the Border Kingdoms could well be changed forever.