Awesome, my login is still good.
I like the idea that Lavos is just on another summit that can't be reached, but the earlier post about him not being visible on the world map screen is a good point. I figure he is hanging around in/under/as? the mountain while his spawn gets bigger and stronger and eventually the spawn (or just the damage already done by lavos) will cause a chain reaction and detonate the planet. That would give the spawn a boost, and would make some sort of sense from a reproductive standpoint. Lavos might not want to leave prior to that because reproduction is too tiring or because it's departure might cause damage on the scale of its arrival (some sort of 'wake', ozone hole, whatever). Heck maybe its means of departure would be to detonate the planet by itself, that would be tough for an immature spawn to survive if it cant take a little Flare
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The centralized spawn locations could be partially explained by the needles burrowing into the earth upon impact. Though that doesn't explain why there would be any on Death Peak unless it was thrust out of the ground and forced some spawn to the surface.
As for whether Lavos is a crotchety old man, dies in childbirth (or prior), reproduces by fission, or wants to repeat the process on another world is pretty much all conjecture at this point.