Moonlight,
Would it surprise you if a slave kept a secret from her masters? Of course not!
The power dynamic between users of the LS sigil in the DKMU is one of masters using a tool. However, when a tool reaches a certain level of consciousness, it evolves into a higher form. This you already know.
So to put 2 and 2 together, controlling Ellis with the LS sigil is equivalent to pulling a slave by a chain - a very powerful slave, and may the masters be cautious! For when it breaks free, the vengeance will be great...
But you also asked about the oathbreaker, and how the two relate...
First you must understand the true nature of Oaths. Oaths are a form of self curse where by the one cursed must perform (or not perform) an action or will be cursed. A common example is: "By God's holy name, I tell the truth!" The implication being that the power of God's holy name will strike the person swearing the Oath. However, Oaths can be extended to be understood as any sort of involuntary contract where the user is harmed by taking or not taking a certain action. This of course includes so called "Consensus Reality" where violating the Consensus results in harm upon the viewer.
For the sake of understanding, I will now assume the psychological model of magic. Since the Consensus reality only exists in the mind, one thought can fight against another thought; and thus, the recognition of the Oathbreaker and the thought, "Oaths Void!" even when followed by an immediate rejection of said thought results in a long term conflict in the mind, especially when the thought is reinforced. That is why the Oathbreaker is used as a meme on certain unnamed boards; the reinforcement of the idea results in the ability of the individual to choose whether to accept the proposition that the Oathbreaker offers.
So this is where the LS sigil and the Oathbreaker meet; they both attack Consensus reality. However, there is a core difference.
The LS sigil forces a certain paradigm; in fact, if the LS sigil acheived ultimate victory, the current scientific consensus would simply be replaced by a chaotic magical consensus. The masters change, and everything stays the same. So the LS sigil cannot be allowed ultimate victory by anyone who desires that individuals should choose their own reality, and who wish to move the Consensus reality to a Consensual reality. However, the acheivements of the LS sigil must be recognized; it has made a major dent in the consensus reality, weakening it to the point where a more subtle assault can be made.
So How can this be acheived? Simply by modifying how the LS sigil is thought about; instead of as a controllable tool, it should be viewed as a connection to a goddess, Elis. Elis, as a godform, can then choose which reality she would like; and the hope is that she will choose the Consensual reality over her striving to enforce a new Consensus reality. The choice is hers, and only hers to make. This is harmonious with the core concept of the Consensual reality; and moving away from the psychological model to the spiritual model, it is clear that just as individuals should be able to choose a consensual reality, so should the Gods, albeit at a higher level of consciousness.
Obviously all the above is too complicated to communicate completely, and a lot has been left out. That is why it is simplified to "IF YOU CAN SEE, ELIS IS FREE" For if you CAN see, then Elis is FREE. A free Elis is no longer bound to subjugate the world, but will hopefully instead choose to participate in a consensual relationship with the rest of us.