The Gift
Wow. That episode ended on a shock moment. Granted, it took them seven shows to get to a fairly obvious place: what happens when you don't just stand around and wait to see what happens, but actively go out and break the design? How much flexibility is there in Fate?
I think this ties back to what I thought about Demetri, that he has two possible Fates and that's why he didn't see anything. (Hell. He's Schrodinger's cat, isn't he?) Zoe, for example, continued to insist that he was there on the beach waiting for her - but we continue to not see his face in her flash forward as confirmation.
The Big Question being asked in the show is "What if you knew - absolutely for sure - what would happen?" Mark's answer seems to be to brood. Olivia's to bury her nose in her work and ignore it. Nikki's is to try and bargain with Fate by being a better person. Aaron simply can't make up his mind. Al's answer was to do anything he could, including self-destruction, to stop it from happening.
It is a fair criticism to ask why it took so long for someone to do something this drastic in response to what they saw. I do think that there could have been people elsewhere in the world who were doing the same thing and we just didn't hear from them. This circle is fairly small, really, and made up mostly of people who are used to knowing the answers, being in control, and analyzing everything to death.
I also have to wonder if some of those "already ghosts" who offed themselves in childish spite playing Russian roulette in some dingy warehouse have also mucked with the pattern. What if they were supposed to die rescuing someone heroically from a cattle stampede or something? Now there will be no one there to save someone who should have lived, right?
It will be interesting to see how this act is folded into the mental arithmetic of the characters.