Destined to Rule

Question: Is the prophecy involving the death of Zeus valid in plots against him?

You mean, if you happen to be a son of Zeus (or helping a son of Zeus) and you're plotting against him, will Fate itself help you succeed? Maybe!

Honestly, this one is totally up to your Storyteller. The ST is in charge of, essentially, playing Fate him- or herself, so whether or not you're The Chosen One is something they have to decide in their metaplot.

Hesiod says that the prophesied son will be "a son to be king over gods and mortals was to be born to her and his heart would be overmastering", and that his mother "might bring forth a thunderbolt stronger than [Zeus'] own", while Apollodorus says she'll "bear a son who would gain the lordship of the sky". Aeschylus is a bit more brutal about it, in which Prometheus claims that Zeus will be dethroned "by himself and his own empty-headed purposes", and that the unnamed mother "shall bear a son mightier than his father" who removes him from power.

Technically, this doesn't necessarily mean that Zeus is going to die, just that he's going to be overthrown by his own son... but let's be real, the Dodekatheon path of succession is one of sons murdering, maiming and imprisoning their fathers, so Zeus knows that this is probably not going to be a pleasant power-transfer experience. Also, Zeus is not about to give up the throne to anybody, so it seems inevitable that war will spring up if he is challenged. He's already eaten people to avoid this, so he's obviously not inclined to be overly rational about it.

Now, if you happen to be this fabled son of Zeus, or you know the guy who is, then sure, the prophecy will work for you. What that really means, in game terms, is that the Storyteller is going to be writing in chances for you to oppose or overthrow or kill Zeus, making your difficulties easier or your thresholds mightier, and generally moving events around to give you a better-than-average chance of succeeding. That doesn't mean you're going to automatically win if you happen to be a lazy ass who doesn't put any effort into it - the Storyteller doesn't owe you success here, even if they're trying to help you in the guise of Fate, and even those who do try hard don't always succeed - but if you want to go for it, more power to you. Other gods and Titans who figure out (through Mystery or just good guessing skills) that you're the big man's downfall may also help you, which is both another form of Fate helping its prophecy come true and an example of opportunists who would love to see the Dodekatheon with a new ruler at the helm (or plunged into chaos, if they happen to not be buddies).

But there's an equal chance that you aren't the prophesied son, so don't go in assuming that if you play a Scion of Zeus, you're automatically guaranteed a ticket straight to the top. There are a lot of sons of Zeus running around, including half the Dodekatheon and several Titans, and you may not be the only new Scion of his, either (smart money says you're not; Zeus has never been good at controlling his desire for hanky-panky). If the Storyteller has chosen some other figure to be the chosen one for plot reasons, Fate will be helping him succeed, meaning that he'll be getting all that behind-the-scenes help and you'll be plain old you. Now, that doesn't mean you can't try to force the issue by going after Zeus and trying to take over yourself - Fate is fickle and prophecies often mean many things, and even if the Storyteller has planned someone else for the role, it's not inconceivable you could take it over - but unless an oracle point-blank tells you that you're it, it's not a done deal. When you have as many sons as Zeus does, prophecies about your offspring could go anywhere.

Basically, it depends on the Storyteller, the story they're telling you, and what you as the player do within that story. If you are Fate's chosen one - because the ST decides you are, because you make yourself into that person, or even because the original chosen gets killed on some wild and crazy outside chance - then it's likely that Fate will back you up, ensuring that its prophecy succeeds. If you aren't, it probably won't, and unless you are (or know) a badass oracle, you probably won't know the difference.

If you're planning to oppose Zeus, our advice is to go for it without worrying too much about the prophecy; the story will shape itself as you go, one way or another. And bring an electricity-proof umbrella.