I could see us getting a rescue arc sooner or later. Maybe more for Vivi, rather than Mosa, but there's a few other characters who could all get saved in one fell swoop. Vivi's the biggest one to me. Pudding's another big one. We also need to follow up with Weevil. And Dragon and Sabo might need backup. And Law and Bartolomeo (and maybe even Kid) all need to get fished out of the ocean at some point. And it'd be interesting if they were all on New Marineford or Mariejois together, just for the plot to happen.
But, personally, I think Mosa's going to turn out to be someone we already know. And I know people don't really like this theory, but I'm saying it again anyway.
I think Mosa is going to turn out to be...Imu.
I'm about...65% sure of this. Which isn't a LOT, but it IS over 50%! I feel like it's more likely than not.
Let's take a look at what Mosa has said, in detail. Because Mosa's only had two "appearances".
In Chapter 1134, Mosa comes across as very polite. I think we can then assume that Mosa has had some form of formal education, teaching them manners. Imu would have had access to some form of education, supposedly.
Mosa mentions a moment that caused them to tremble with fear. The memory of the event is still causing them to tremble, so we can probably assume this event happened fairly recently. Back in Chapter 1122, Joyboy's Haki Knot went off, and we literally see Imu trembling in their butterfly garden. This event happened recently enough that Imu could still be affected by it.
Loki gives Mosa the advice that they should have just slaughtered everyone causing them problems. It would be very fittingly ironic if Loki was giving this advice to someone who's about to do something similar to his own home island. There's a level of dramatic irony to Loki giving this type of advice to Imu that I think Oda would enjoy.
But, Mosa doesn't want to do something like that. They don't want to kill everyone, even if they cause them problems. Mosa seems like a fairly gentle person by nature. And, despite what some people may think, that actually lines up pretty well with Imu's actions on Elbaph. Imu ordered the God's Knights to take hostages in order to get the Giants to obey them, when they could have just ordered a massive show of force or even a Buster Call. And by the end of Chapter 1150, Imu orders the Giants that have been flipped to NOT destroy everything, because they want to rule this land. "Imu" is a bit more violent than "Mosa", but they still seem to share the same underlying core values. Both prefer to protect lives, rather than waste them.
Also, Imu actually turning out to be kindhearted and quiet actually fits a person who's spent the majority of their time in a butterfly garden, hiding away from the world in secret. Imu does not seem to be a cackling megalomaniacal supervillain. Imu seems to be a shut-in or hikikomori. Imu only seems to be in a hurry now because Luffy and Joyboy's Haki is spooking them. Before, Imu seemed content to just let the World do as it may, for the most part. Imu doesn't seem to seek glory or power. Imu just seems to want peace and quiet, as far as I can tell. Mosa asking for Loki to not yell, actually makes sense if it turns out to be Imu, who spends most of their time in quiet in the butterfly garden.
Now, lets move on to Mosa's only other appearance, Chapter 1151. Mosa calls to say goodbye, right AFTER Scopper gets impaled and thrown off the World Tree by Gunko. This is right BEFORE Imu takes possession of Gunko's body in Chapter 1149. We see in the beginning of Chapter 1150 that after Imu takes control of Gunko's body she sends out a massive Haki Wave that covers Elbaph, almost immediately. This is the same Haki Wave we see Luffy and everyone reacting to down in the "Underworld Layer" at the end of Chapter 1151. So, given that Luffy and everyone has the time to react to Scopper's "arrival", then listen to Loki's conversation with Mosa, then start to treat Scopper's injuries, all BEFORE Imu sends out their Haki Wave, that says to me a little more time passes than we're lead to believe from Gunko's side of things. So, in Chapter 1149, after Scopper gets impaled by Gunko, it seems like more time actually passes between that event and Imu taking possession of Gunko than that chapter seems to imply. Maybe it actually took a few minutes for Gunko's memories to start to come back, which could explain the time difference on page? Maybe this is all part of that "time dilation" theory, with different "Layers" of Yggdrasil having different rates of time flow? (Which I'm still doubtful about, but it's worth bringing up.)
So, I think Imu called Loki to tell him goodbye, right BEFORE taking possession of Gunko and starting the conquest of Elbaph. Imu is saying goodbye before they have to put on their "work face" and take over Elbaph. Imu likely knows that they'll never be able to talk like this again. And that Loki could even end up dead, due to the takeover. Because calling to say "goodbye", right before Imu actually arrives on the island that Loki's on? That's good dramatic irony, right there. "Mosa" won't be able to talk for a while, because "Imu" will be too busy annexing Elbaph.
There's also the honorifics. Loki calls Mosa, "Mosa-kou", in Chapter 1134. "Kou" is a old fashioned honorific meaning "Lord", which can sometimes be used sarcastically, like "M'Lord!". Qilingham also refers to Imu using a old-fashioned honorific, "ontai", meaning "boss" or "beloved leader", in chapter 1151. Both of these characters are being referred to using old fashioned, almost "ancient" honorifics that are not commonly used in Japan. Imu is most likely over 800 years old, and likely has old fashioned tastes. So if Imu WAS Mosa, it would kind of make sense for both characters to have a certain fondness for old-fashioned titles and honorifics. It probably reminds them of their past.
https://jlearn.net/dictionary/公-こう
https://jlearn.net/dictionary/御大
"Ko" could also be a board game reference. "Ko Fight" is a situation in the board game "Go" which is a kind of stalemate or tug of war between the players. And so far, Imu's powers seem very board game based. Using items from Othello/Reversi and Clue/Cluedo. So, this does feel like it lines up with foreshadowing that Mosa could be Imu. And it reflects the situation that Imu will likely be put in, once Luffy and Loki show up. Imu will likely have to go back to Mariejois, or else be stuck in a endless loop of back and forth matches with Luffy, with neither really being able to get a total victory over the other. Calling Mosa, "Mosa-ko" could be a very cheeky reference to Imu's board game powers.
https://en.wikipedia.org/wiki/Ko_fight
http://yeefan.sg/weiqi/howtoplaygo/howtoplaygo05.htm
reddit.com/r/baduk/comments/1ktkqfs/the_most_fascinating_go_position/
Loki also seems to be kept away from fighting Imu, at least until the very end of the arc, by Oda. Why would that be? Well, what if Loki would recognize Imu's voice as Mosa's? The "shaggy" Transponder Snail could just be explained away as being a cold-resistant model, instead of being based on Mosa's actual appearance. But, the voice should be the same. Could Oda be delaying having Loki join the fight up above because Loki would recognize Imu's voice, and Oda wants to save that for a big reveal later?
Also, take another look at both of their names.
In Japanese, Mosa is written as: モサ
And, in Japanese, Imu is written as: イム
Both names just so happen to be made up of two katakana. They aren't the same "letters" or anything. They don't even really look alike at all. But, it is a weird coincidence that both of these characters have "names" that are only two characters long. And both names are two syllables. It's not much, but it's a little something. *shrug*
Basically, what we're seeing here is the difference between Imu's "public face" and "private face". "Tatemae" and "Honne" in Japanese. "Mosa" is Imu's private face, where they can express their feelings freely. All their doubts and worries. Because Imu is anonymous and no one is counting on them to lead. "Imu" is the public face. The strong, intimidating leader. The one no one dares defy. The one who can't let anyone get too close to them. This would explain why their dialogue styles are a bit different. One's more polite and one's more demanding. But, I think that's a reflection of two sides of the same person. Not two completely different people.
https://en.wikipedia.org/wiki/Honne_and_tatemae
As for how all this originally came about? How did Imu start being "pen pals" with Loki in the first place? Well, we do know the World Government wanted Loki to join the God's Knights. Supposedly, the Government could have been spying on Loki and keeping him under observation, just to make sure he stayed chained up. Maybe Imu grew to care about Loki after spying on him for 6 long years? It's not like Imu has many other people to talk to. It's the Gorosei, MAYBE the God's Knights, and that's about it. And it kind of makes sense for Imu to bond with a Giant, since they're both so long-lived. Maybe Imu wanted Loki to be a God's Knight BECAUSE they became such good friends without him knowing about it? Maybe part of the reason "Mosa" called to say goodbye was BECAUSE Loki turned down Imu's offer so harshly? Maybe Imu's feelings got hurt a little?
So, yeah. There's my case. Loki can't go off and save Mosa, because "Mosa" is the one attacking Loki's home island. Although, I do believe that Imu will end up getting "saved" by Luffy (and maybe Loki). If Imu turns out to be not that bad of a person, and was just forced to make some tough decisions over the years, someone's going to have to get Imu out of the "gilded cage" they're stuck in. Imu could end up being the last "princess" we have to rescue in this story.
And, at this point, I feel like Loki will figure that out before the end of the arc. If this turns out to actually be the case. I'll admit, I could be VERY wrong. But, "sympathy for the devil" is a phrase for a reason.
