I assume you don't mean the character returns to their original timidity, rather to an "older and wiser" state. As such the structure seems something like a Hegelian dialectic (thesis/antithesis/synthesis or abstract/negative/concrete) played out by a single character.
I haven't read Chuck Palahniuk's novel, but the film Fight Club runs along these general lines. The extreme aggression, shall we say, outlives its productive usefulness and eventually is tamed by a kind of assimilation.
Hamlet is by nature passive. He kills Polonius and drives Ophelia to suicide with his wild aggression, then reins it in a bit (albeit not a lot) in order to focus on his real target. Of course he's not "responsibly" anything at the very end, he's dead.
Michael Moorcock's various "eternal champion" characters often follow a pattern of being spurred by events from passivity or naivety into an act of excessive aggression, leading to a lengthy period of regret. Of these, both Elric of Melniboné and John Daker / Erekosë receive a classic external "push to action" early on, and destroy entire civilisations before reaching more serene states.
You could perhaps say that Bathsheba Everdene follows a path of this sort in Far From The Madding Crowd by Thomas Hardy. She's not quite timid initially, but she's less directly assertive until her circumstances change. Then she does become more headstrong and rash until disasters result and she finds a more even keel. I suppose her final state isn't really a reversion, more of a transcendence of her previous progression.
For an example where the protagonist ends up more passive than they started, consider Nineteen Eighty-Four by George Orwell. Here there's no synthesis, Winston Smith's recently-found passion and activity are simply beaten out of him.
The various authors here haven't necessarily set out explicitly to write a character overshooting and then reverting, although where they learn lessons this is no accident. The characters follow something like the pattern you're looking for, but the importance of this fact to the structures of the stories varies.