The Azumabito clan / Hizuru want to shelter Mikasa because she's half Hizuru (Asian) from her mother's side. It has nothing to do with her being an Ackermann, which is why they do not care about Levi.
I know I already mentioned that theory of mine a while ago, but I still think there is a lot more to Mikasa than we've been led to believe, and that her being the child of an Ackerman and an Azumabito is actually
extremely important.
I think there's a good chance the characters will find out that Eren can only activate the power of the Coordinate while in direct contact with a Titan with royal blood (that would be Zeke, right now). That the power stops working
right away when said contact ceases.
And I think Armin will be there to see that, and will do what he does best, that is to say, connect the dots.
How come Eren could still use the power of the Coordinate for hours after he punched Dina's palm? We simply assumed it was some kind of lingering effect, but if there's no such thing, why?
Who was Eren in contact with when he sent those Pure Titans after Reiner and Bertolt?
Who was Eren in contact with when the scouts were on their way back to Wall Rose and the Pure Titans kept ignoring them to go after Reiner and Bertolt?
I think Isayama didn't have Mikasa get hurt just to raise the stakes during that sequence: it was so Eren would then have to carry her, and so they would ride on the same horse on their way back.
"But Mikasa isn't a Titan with royal blood!"
We've been
specifically told that the Ackermans are a by-product of
Titan science, and that some of them (like Mikasa, Levi or Kenny) experience an awakening that allows them to use the power of
the Titans even in human form.
So that's one half of the equation taken care of already.
As for the other half...
Kiyomi told us that over 100 years ago, Erdia and Hizuru were allies. That the son of Hizuru's shôgun used to have "a close relationship" with the Fritz royal family. That although she didn't really know the exact details because of the chaos caused by the Titan War, his descendants remained on Paradis island following said war.
And you know how countries used to form alliances back in the day, right?
I'm thinking the Azumabitos that remained within the walls had Fritz/royal blood. They were a separate royal bloodline (which might also explain why they were persecuted to near-extinction in later years, in fact?).
(Also, I'm not
so sure Kiyomi is being truthful when she claims not to know why those Azumabitos stayed on Paradis island after the war... We know she desperately needs the Rumbling. And if Mikasa has royal blood, it's no wonder Kiyomi cares so much about her survival and instructs her to "escape on their ship at once should anything happen": she is a spare key to the Rumbling that no one else knows about.)
So... yeah. That would do the trick.
Eren wanted another way to protect Erdia that wouldn't involve turning Historia or her children into Titans, and there it is.
Perhaps not so coincidentally, a while ago, Isayama answered what, at first glance, looked like a purely theoretical reader question:
Q: If someone had both royal and Ackerman blood, which side would manifest?
A: I'd say both sides would.
Anyway.
Armin was right there when Eren used the Coordinate while in contact with Mikasa.
He was right there when Kiyomi gave us that short history lesson about Erdia and Hizuru.
He was right there when Eren said the Ackermans could tap into the power of the Titans.
And he's right there now that Eren and Zeke are about to finally use the power of the Coordinate.
He could connect all the dots.
That would give Armin something to do.
That would give extra meaning to Eren and Mikasa's relationship.
Basically, the original trio would be front and center for the end game of the series.
Prove me wrong!
