Board Thread:Spoilers!/@comment-24674051-20161004210512/@comment-24674051-20161005160824

That's why I put this out there now. Let's discuss each character and try to guess BEFORE we get the official reasoning.

I had a thought on Captain Nemo, which I will also put in the Episode thread. Aside from Nemo, another very important thing from 20000 leagues is the Giant Squid. So I will place the flashback to sometime after Killian encountered Ursula, and the plot derives from Hook enlisting the aid of Captain Nemo to capture a giant squid in order to harvest some squid ink to use against Rumple. Things start to go south quickly, and Killian abandons Nemo to deal with the squid. The Nautilaus gets dragged to the bottom of the ocean, and some event transpires that makes escape to the LoUS an option for Nemo, one that he quickly avails himself of to wait until he can exact revenge on Killian.

So the main reason is that Nemo wanted to survive until he could exact his revenge.