Daniel's parents were active conservationists who met, married, and had a son while still in college. As devoted eco-warriors with a strong love of life, they traveled around the world, taking young Daniel with them to protest everything from deforestation and whale hunting to corruption and injustice. An accident when he was twelve deprived Daniel of both his parents and left him in the care of a relative. Going from a loving family to the cold, distant care of his uncle, Daniel retreated from people and found happiness in the woods and mountains. A Surprising discovery during a cliff climb gave him a universe of possibilities. With that discovery, the question he faced then became What does an environmentally conscious loner do when he stumbles upon the most dangerous intelligent tool in the universe? His answer: Follow what his parents tried to do, and start fixing the world.
Of course, most people would not agree with how he goes about doing it. Fixing the world is nice and all, but then why stop there? Hopefully, he'll remember the two great adages of the OP character - "With great power comes great responsibility" and "absolute power corrupts absolutely".
Now, as everyone knows, all stories should have a beginning, middle, and end, and this is just the beginning!