Re: Elbaf and Jormungand
It could be J√∂rmungandr, but that description can also be applied to Fafnir and N√*dh√∂ggr, since dragons in Norse mythology are pretty much oversized snakes. But let's stick to J√∂rmungandr, since that's what you asked.
One thing that just pops into mind when thinking about it, is that one legend says it is so big it encircles the entire world, grasping its tail with its mouth and when it lets it go, the world will end. Funny thing is, we already two things that do that: the Grand Line and the Red Line. Both are smack in the middle of the ocean and have a very serpentine look and, if either is altered in significant anyway, it would mean major chaos. It's very unlikely it'd be true, since it seems the snake and the giants fought against each other and it'd very odd seeing giants fighting the Red/Grand Line.
What I can see Oda doing is using the legend of √ötgarda-Loki, since it screams Strawhat shenanigans. Once upon a time, Thor, Loki and Pj√°lfi traveled to √ötgard and, along the way, they decided to rest, unknowingly settling inside a glove of a giant named Skr√Ĺmir. After that, the giant follows them, just to trick them and take their food. Starved, Thor tries to kill the Giant but fails because the giant uses a mountain to shield himself.
Once they arrive to √ötgard, a castle so high that the three had to look vertically to see the top, its king, the giant √ötgarda-Loki, challenges them with contests based on deceit. Loki enters an eating contest against fire itself, Pj√°lfi runs against the Giant King's mind and Thor enters in three contests: trying to empty a drinking horn connected to the sea, lifting to the air cat which is J√∂rmungandr disguised and fighting against Elli (old age personified).
They fail every contest, but the Giant King now respects them and tells them he was Skr√Ĺmir, the giant they met before. It's not because he suddenly had a change of heart, he knew perfectly well they could never win the contests, but the thing is they did exceptionally well for his expectations, being able to lift J√∂rmungandr enough to take its paws off the ground and creating a vast sandy beach where the coast was due to drinking so much. Thor tries to challenge the Giant King, but as soon as he tries to, the giant and the castle disappear.
So the Giant King could be also challenging his own people in Elbaf, thus making Dorry say that (since the king could reveal why the damned cat was so heavy).
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