Garrett at 2010-10-14 18:31:55:
I think the "Why does this story have to happen to this character now?" question is awesome because it ultimately contains within it an enormous coincidence. This is of course in the context of the entire life of the fictional character, but it really is a coincidence. We just happened upon this character at the exact moment something completely life-changing is occurring.
But that's what a story is. To borrow from Scott's penultimate analogy, a story in the context of screenwriting occurs at the exact moment the animals appear to our protagonist. We don't see his childhood or parents or senior thesis defense. We don't care about that. What we're interested in is the moment he sets his sights on that prize lion in the middle of East Africa. That's what we care about and here we are right there with him. What a coincidence.