(please excuse the massive wall of text, couldnt think of a way to more elegantly change Idris)
Idris Talfryn walked through the woods, contemplating his existance and purpose "I dont know who put this damn thing in my head, and i dont know what its for, but i know it makes me rather....impulsive". Thinking back to his attempted assassination of Stiers and the thought of almost holding Tor made his heart quicken "It was like i couldnt control myself, that damn fried portion of my brain just told me i NEEDED that cursed sword, and damn whoever gets in my way"
Idris laid under a tree, "I dont want to know what it will make me do next, i dont hate anyone here, yet i keep getting these urges to kill people to increase my own power, for what purpose, i dont know. I should just off myself, that will dissapoint the nether out of my handlers" At the thought of suicide, the affected portion of his mind put up protests, forcing him to think happy thoughts until he was able to push them back through sheer force of will.
In struggling with his fractured mind, he attempted to end it by grabbing at a colorful mushroom, one he hadnt seen or used in poisons before, and devoured the entire cap, in seconds the altered portion of his fractured psyche ceased protesting, followed shortly after by the normal portion of his mind stopping too. The woods around Idris began melting with colors running every which way, and the world began to spin. Idris looked at his hands thinking he saw them turning into paws, and when he tried to scratch at his hands and arms to remove the furry appendages his skin split and shed like a snake, his face looking at him from the top of a pile of skin. Emerging from the splits was tufts of golden fur, eventually revealing itself to be an entire Lion body. Idris attempted to calm himself in vain, "ok, ok, ok, im just hallucinating, im no druid, im not turning into a lion, there are no mushrooms that turn you into a lion."
Images flashed around Idris' head, his blade futilely plunging into stiers' back, stiers attempting to revenge kill him repeatedly, tor, his captors, the experiments. And than everything went black. In a panic, Idris began running, not able to see where he was going and not much caring, just trying to escape whatever it was he just forgot......FORGOT..... suddenly he realized he had forgotten what had been troubling him all this time, and shortly after that, he forgot he was human and embraced being a lion
Just as Idris was getting comfortable in his new form, even succesfully chasing and capturing a deer, he had another flash of images. This time it was of things he did not yet know, knowledge of healing herbs instead of poisons, images of himself smoking and consuming dozens of different things, not just the tobacco he was accustomed to. And images of him sharing these things with other people, of him curing the dead and dying instead of digging a knife into their ribs to rob them. After a time his lion skin began to pull back into a cloak of many colors, revealing a shield strapped to his arm with a face painted on the front, a massive amount of herbs rolled in paper, bloodshot eyes, and new feathers protruding from his hair. These changes didnt trouble Idris now though as he inhaled on his comedically large "cigarette", and he didnt spend time contemplating them as he stumbled towards town. For the first time since he was a child, he didnt have a care in the world.