So I beat the Octo Expansion and absolutely loved it. However, I am a little confused on the overall story. I think the game did a great job of fleshing out Pearl and Marina's characters, but the main story itself left me with questions.
For one, CQ Cumber says that deep sea life is forbidden entry to the promised land unless they pass those tests. But...who made that rule? Was it the Inklings? Was it Commander Tartar? Who designed these tests anyway? How'd Cuttlefish, Agent 3, and Agent 8 get to the Deepsea Metro Station in the first place? Why exactly did Pearl and Marina decide to help? They aren't agents, so they weren't assigned to do so. Were they just bored and wanted to help out? Why was CQ Cumber the one monitoring the tests? It made me think that maybe he was the ultimate bad guy pulling the strings, but he wasn't. How were so many Octolings making it to the surface? Story-wise, they couldn't all have been like Agent 8 and passed all the tests. If Commander Tartar just wanted to kill Agent 8 and Cuttlefish, then why go through the whole test thing? Couldn't there have been a more straight forward method? Why were the Octolings green and hostile toward Agent 8? Were they mind controlled?
From the developer noted on Tumblr and Twitter, the Octarians we face throughout have been "sanitized," and are thus mind controlled by Tartar. How he got ahold of all of them is anyone's guess.
I'm guessing Tartar kidnapped Cuttlefish, Agent 3, and Agent 8 as test candidates to eventually become blended into his primordial ooze should any of them succeed in getting far enough. If they failed at best they could have been sanitized or just left alone to live like Iso Padre.
Not sure about CQ Cumber's role in all this, but I'm guessing it's sanitized to serve as Tartar's zombie train conductor/test proctor.
Pearl & Marina
could have been just vacationing or whatever around Cuttlefish & 3's last known location, due to Pearl and Inklings in general seeming oblivious to what an Octoling is. But again, I'm guessing on that just like everything else.
Meanwhile, I'm not sure why it took two years for all the player character octolings to reach the surface, but part of me is guessing that they could have recently heard it during the second game's boss fight as Calamari Inkantation was performed before a stadium audience.
So much guessing...