Just a random thought that occurred to me.

Boethiah's sphere is "deceit and conspiracy... treason, and unlawful overthrow of authority," which sums up rather nicely the Aldmer view of Lorkhan as a trickster and betrayer, as well as the mythic role of the Rebel in general.

One can also make the argument that Boethiah is a god of ambition and mortal undertaking, given that On Oblivion notes that she "inspires the arms of mortal warriors," as well as this gem from Boethiah's Proving: "I am alive because that one is dead. I exist because I have the will to do so. And I shall remain as long as there are signs of my handwork, such as the blood dripping from this blade."

Both use a serpent as one of their symbols (Shor's totem animal is the snake, Boethiah's realm is known alternately as Attribution's Share or Snake Mount, and her statue in Skyrim has her draqed in serpent's tails).

And, Boethiah was the original god-ancestor of the Chimer, who convinced the prophet Veloth to lead his people east to Morrowind, where the Heart of Lorkhan lay waiting for the Tribunal.

It just seems like an awful lot to just be a coincidence. Could Boethiah perhaps be a fragment or shadow of Lorkhan, or maybe a leftover from a kalpa where Lorkhan didn't participate in creation?

I used to make several dualism connections between different et'Ada and regarding the 12 worlds. And I found it interesting that Molag Bal-Boethiah conflict shares some common points with Dragon-Serpent. The former is Tyrant-Usurper while the standard enantiomorph pattern is King-Rebel. Tyrant shows some certain way of how a king acts as a king, and Usurper is how a rebel acts as a rebel.

Sometimes I think both Molag Bal and Boethiah never taking part in the Creation, and their deep involvement in Mundus, at least of the current kalpa, are due to their similarity with Dragon-Serpent. Maybe they once shared the same world of the twelve with Dragon-Serpent.

In fact these dualism themselves are also overshadowed by the Anu-Padomay conflict. That the Aedra part define "What is King/Rebel/etcetc", while their Daedra conterparts define "How to become King/Rebel/etcetc". The similar pattern shows in Julianos-Dibella and Hermaeus Mora-Mephala dualism. It seems to me that Julianos and Dibella define "what is knowledge" and "what is connection/attraction", while Hermaeus Mora and Mephala define "how to gain knowledge" and "how to establish connection/attraction".

Some Daedra are more aligned with Lorkhan (more or less the Dunmer's 'Good Daedra', who teach them the Endeavor), some more with Aka (Jyg, Meridia, etc.). Some like Molag and Dagon are just so bats that they don't align well with anyone. I suspect this is the nature of the Aurbis, inevitably.

Vivec's death-benediction ("...in the House of Boethiah where we become safe and looked after"), however, is a good indicator of Boethiah's lasting role in the 'Lorkhanic' pantheon whenever MK picks up a pen.

Then gamesas uses his character, and he turns into a human-sacrificing psychopath again.