Why would the old gods vanish?

Right. Neither my co-writer (for want of a better term) and I could come up with a reasonable answer to this dilemma, so I thought I'd throw it out here to NaNo fantasy writers and see what ideas come up.

This all takes place in the world of Gaia, our earth, which is in modern times (the war happening around 2010, and the gods returning around a hundred years later, give or take a little), where humans exist much as they are today, but there are also lots of other realms unseen by them. Olympus is a city floating in the sky. Also, many different mythologies exist in their own realms, every so often interacting.

The known fact is that the trickster god Loki decided to stage a fake war, turning thousands of humans into demons in the process and enslaving numerous previously existing demigods and monsters, and then attacking Olympus.... and then was defeated and chained back up by magic in a safer form, thus saving the world, all that jazz. Great. But not the point. The point was that during all this chaos, the Olympians vanished, en masse. None of the characters know why or even realize it until much later. Also, some of them, mostly the more minor ones, like Iris and Dionysus and Eros, show up later. Some of them, like Eros, even seemed to have died and left their families behind.

Then, many, many, many years later (after this past year's NaNo novel, actually), a certain group of the Cousins....

(Sidenote: the Cousins are the demigods, and other younger, modern, and more humanlike relatives, generally called in the collective because, well, it's a running joke that due to the twisted family tree, no one can figure out exactly who is related to whom and how, and anyway cousin is generally safer than making dangerous assumptions amidst people who could wield lightning bolts or tidal waves.)

... and Loki were sucked into an alternate dimension by a portal dysfunction, and when they're finally able to come back, Loki is separated from the others and greeted personally by Eros, who brings the message that, yes, he still hates him, no, he isn't going to kill him right now, despite the fact that he really wants to, and that, oh, yeah, all the gods are coming back.

And still no one knows why this happened. I have a feeling that it's important to figure it out, though. It could shape the future of the whole world. Do the gods know something that everyone else doesn't? Are the gods dying? Is the world changing again?

So far, our ideas include that maybe they were off in some godly pouting zone after taking a vacation to nowhere, confident that all the Cousins wouldn't let the world crumple in their absence, generally feeling like they deserved a nice break after thousands of years of being all godlike and then being generally forgotten by mortals. Or maybe they settled in other worlds without any obligation to return because they had their eyes opened to the fact that their own world was going to end someday soon and wanted to avoid having to deal with it. Or maybe they were just sore losers over the war.

I'm just not sure at this point. What's your opinion? Maybe something else could be going on? Seriously, I'd love to hear any outside opinions. :)

Maybe something that was crucial to their power was destroyed in the war, something that would leave them vulnerable. They could have left to protect themselves?

Maybe they got into a big fight and broke the bifrost bridge and it took them this long to finish their fight and repair the thing. Maybe they got into a war with another batch of Gods from some other world and it took them this long to kick but and get done. Maybe they decided to create some other world and decided to collaborate, and it took them this long to decide that they suck at collaboration and that they should go back to the original world and have a closer look at what they did right there since they screwed this new one up so badly.

Maybe they used so much energy in the war that they just kind of didn't have the strength to hold a material form for a while. So they were still there, they were just kinda disintigrated. I don't think I'm explaining this well.

What I'm thinking is that, basically, they don't have physical bodies naturally. They're literally the essence of whatever they're the god of. So Zues is the essence of thunder, Hades is the essence of death, etcetera. After being all noncorporial for millenia, at some point they got the idea of making physical forms like the puny little humans they'd been watching over, only of course much better. So their bodies are actually just constructs of their will and their power. And then they used up too much power, and weren't able to hold themselves together.

I don't know. It made sense in my head, anyway

Maybe they got bored. Finicky gods in need of new entertainment.

A few hundred years of playing with humans, and it eventually lost its intrigue. Playing games with the humans became pendantic and less of a challenge. They left to discover new species, new planets, new toys - anything to fill the boredom of their immortal lives. New toys only stay new for so long, though, and they began hankering for the humans again.

Maybe their Dimension-Eating Holy Hand Grenade had a bigger blast radius than expected?

I've been thinking over this some more now. (Thanks for all the posts so far, and I'd totally love to hear more opinions, ideas, so please don't let my walls-of-text stop you. =P)

The gods definitely would have to recover from the war to an extent - some more than others. None of them went head to head with Loki, and generally the pantheon had minor deities doing all the footwork, as well as human heroes and demigods and other allies.... And the majority of them vanished to wherever long before the war even came to a head.

Also, I realize now, thinking of what Nialon said, that Olympus was razed to the ground and destroyed around the same time that the gods vanished, and its reconstruction was underway by the time that they returned. So perhaps that was part of why they came back - because their home was calling to them again somehow. I'm not sure, but it sounds like a start.

And definitely there were more motivations from the individual gods themselves, and more conflict within the pantheon. I can't imagine Aphrodite, for example, ever agreeing with Athena over whatever they were all doing in the meantime. Especially if some of them were wounded, and others excited, maybe, over new toys, and maybe a couple like Hermes and Artemis seriously trying to figure out what was going on with the state of the world (and other worlds.) (They do really suck at collaboration.) Some of them would still be in shock, like Apollo. I'm not sure exactly how Zeus and Hera would react to all of these things, and I think my co-writer already has plans for Dionysus hanging around.

Some of the gods that did personally interfere, such as Eros, did actually become, for want of a better word, un-guised. The gods are the essence of themselves. It's what makes them more than just magical humans, and why they don't have to be believed in to keep existing. Their essence is a core of selfhood, I suppose - a spark in their soul that's wrapped up with everything that they are or were or will be - not just their affinity for magic, but their symbols and stories and everything from their giant destiny down to the littlest things like favorite color or animal. Human souls are made differently, so they don't have the 'spark' of inner essence. So when Eros's physical guise was destroyed, he went back to being an Abstract Apotheosis instead of Anthropomorphic Personification, returning to all the Love in the entire universe instead of Love in one person and one god. The same thing would happen to Thanatos or Morpheus if that happened to them, I think... But I don't think that happened to any of the gods in the pantheon itself so far, though.

Other worlds might make sense. Groups of characters have world-hopped before through dysfunctional portals and the like, so that could be possible. Wonder how the war might have affected those worlds....? 0.0

Still have no idea what I'm doing, of course. XD Maybe I really could use a holy hand grenade... >.>

Perhaps the old gods left in disgust and let the new gods fend for themselves. (Lock them in a room and let them sort it out).

Perhaps the old gods are quietly observing and not interfering. That the humans are screwed might not be relevant to the divine.

Perhaps the old gods are the new gods, or rather the new gods are different aspects of the same force as the old gods. When the new gods become more relevant, the old gods fade away.

Perhaps some new faction imprisoned the old gods as their powers were diluted by time and new powers.

Perhaps the people stopped believing in them when faced with the more immediate problems of the new gods.

Everyone bailed because God (as in He Who Is Called I Am) is coming and is going to be totally pissed that a bunch of wannabe godlings have been playing with his toys. I mean He was nice enough not to destroy the Olympians and other so-called deities with a thought after wishing them into existence once day when He was really really bored. But just because he leaves the Earth for thousands of years to go attend to various other projects (it's a big cosmos) doesn't mean a bunch of guys who are just humans with superpowers can screw with his stuff.

That or the stars are finally aligned properly and Cthulhu and other real gods from beyond the stars shall arise. When this is so all of mankind and the pathetic beings it calls gods shall be crushed underfoot like bugs. Literally, as the Old Ones will probably not even notice humanity and the gods as they walk upon the earth once more. Basically the jist here is that such beings HAVE NOTHING TO DO WITH HUMANITY OR HUMAN CONCEPTS and would simply destroy any mortal races and the gods inpiring/feeding/born of them not from spite but indifference. How many bugs have you stepped on in your life. Would you even care to know?

Or Lucifer comes and kills them all in a hotel...no wait they did that one on Supernatural...lame...

Or the God of Monothiesm if born (as in representing the concept of their only being one god) and is instinctively driven to kill every other god in existence because they SHOULD NOT exist. He/she/it has no plan for afterwards. The fact that other "gods" exist is enough to justify eternal war against them. Several of the other pantheons were already taken down without anyone realizing. Maybe your characters go to see the Egyptian gods in their desert and find nothing but the aftermath.

Just a few ideas off the top of my head there...