That is very good and well thought out headcanon. Two things that could help your theory-in 80s Voltron there was Commander Cossack who had sort of friendship with Haggar, so idea of her being friendly with at least one general isnt old. Also in season 1 I think Zarkon mentioned smth how he trained Sendak.

You should have seen me pre-season 3 going Cossack is coming back and this time he will be in love with Haggar. Even named it Cogar in case he does show up, while using Horan for Haggar/Coran. Also been going with Raht/Haggar as well. Basically all the buff men are in love with Haggar in my head. 

Yes Zarkon did train Sendak it’s true, and he’s been his top man for as long as the empire has been around. For that reason I think Sendak is familiar with Lotor, due to the eternal child being by his side and seeming to never age while Sendak takes the mantle of being Zarkon’s protege. 

So far the two commanders that have shown incredible loyalty to Haggar seem to fill in for Cossack, since some of Cossack’s character traits are now in Zethrid, so I really hope the two of them get close for that very reason. 

Acxa will be the head of Sincline

Since there have been many speculations that Narti will be back, and that the next season will mark the point of the story where the villains win, it’s only fitting to bring this up now. 

Acxa is the foil for Keith, while Lotor is for Allura, Ezor for Lance, etc. We have also seen foreshadowing of the positions of team Sincline way back in seasons 3 and 4. 

Initially Acxa is the right arm and Narti is the left

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Once the shit goes down the positions have changed. We have Ezor moving to the right arm -like Lance did- Zethrid in the left leg like Hunk, and Lotor in the right leg, just like Allura. 

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There’s a point to be made about Lotor being tied into the right leg, as Haggar has been pulling the strings with all his movements in season 5, and we all know that we should never underestimate Haggar’s ability to get what she wants, and what she wants is for her son to be under her control just like he always has been as a child. 

There’s a high possibility that Keith will be back in black next season, and tailing a comet has already shown the parallel between his leadership and Axca’s. Acxa has shown time and again that she’s a natural leader, who like Keith, steps down for their mentors to take over. Both move up from being the right hand to being the leader of the giant robot. 

The key to the Sincline formation is Haggar. She has the ability and potential to gain the secrets of Oriande, most likely corrupting it on the way. And we don’t know what she’s gaining so far from secretly guiding her son’s victories. Narti also was implied to have a connection with her via Kova or her abilities. Just as Haggar brought back Shiro and Zarkon, she can do so with Narti, especially if she gains the ability of the life givers.