I had this brief plot idea polished some by the LintKing.
A great mage is born, a mage whose power to summon elementals of the Earth itself. He (or she: gender is irrelevant to the adventure as it stands) is harnessed for use by Generic Evil Corporation from an early age, but as he gets older, he begins to hear from free elementals that he is a danger to himself and others. He begins to doubt himself, and quakes, eruptions, the like begin to occur. His maladjusted sense of responsibility begins to drive him slightly bonkers.
At some point, he is "rescued" (the word is probably closer to "stolen") by a group of 'Runners, whose magically-inclined Mr. Johnson has the Earth mage lifted into a plane, where he cannot access his powers. For many years, he is simply transferred from plane to plane. Then, something happens to Mr. Johnson, and his whole project is cancelled.
The scenario now kind of splits into two situations:
ONE) The mage is now quite maladjusted and is one of the most potent threats the world has ever seen. You might even need to hire a Toxic Juggernaut Shaman to help take him out.
TWO) The mage is now quite reformed (after all, this is a great opportunity for therapy) but the Earth misses him. He is overwhelmed by the energy, and there are magical repercussions worldwide... leading him to be used as a tool for someone else.
Did I ever tell you about awakened Jell-O molds?