Summoner

As the old dwarf rounded the corner of the street to get home, several thugs stepped out. Fear flashes on his face for only a moment before he grins. The thugs, believing the man senile, threaten his life if he doesn't give up everything he owns.   The beating of wings fills the air moments before a loud thud hits the ground behind the thugs, rattling everything. They turn to see what made the noise, dropping their knives in fear as they see a large creature swelling up behind them.   Standing a full nine feet tall, the creature only vaguely resembles a great, winged bear, with long, humanoid hands. It grasps the first thug as they try to bolt, lifting it by it's chest and snarling into it's face. "It's okay Jazareen, let him be. He's just a desperate fool."   Summoner's are born with an unknown companion, known as an eidolon. As children, they display an unusually strong preoccupation with their imaginary friend, only to have their imaginary friend take corporeal form as they reach their teen years. For many, their powers never grow beyond this, simply being normal folk with unusual looking pets, but for those that push their connection further will find a powerful being they connect to, body and soul.  

Mysterious Origins

A summoner's companion is something beyond explanation. They aren't any form of spirit or being known to any sage, and even the god's are silent on their origin. The best guesses describe them as extensions of the person's soul, and this seems to hold some truth with their shared experiences.   Many believe that a summoner is a weird mutation of a sorcerer. Many summoner's cast spells as sorcerer's do, but far less effective, possibly due to their connection to their Eidolon. They cast limited spells, focused mostly on the power of their eidolon. What magic they do use is mostly defensive, as the shared magic between them can cause a summoner to suffer the brutal punishment inflicted on their eidolon.  

Playing in a setting

For D&D 3.5/Pathfinder, you can use the class as provided in the SRD.   For D&D 5e, use this link: Summoner. Rules for crafting your summoned creature can be found here while spells can be found here.
  No rules have been developed for playing a Summoner in FATE as of yet.