Here's my own analysis of the LADS LIs as mirrors as of each other. We've all heard the character analysis that Sylus and Xavier are foils, as well as Caleb and Zayne, but I haven't heard anyone talk about their mirrors. Sylus and Zayne are mirrors of each other because they are all about desire, control, and destiny. Through Zayne's story and myths, we see that he is supposed to be a being of control but his desires take over when he's around MC, and he loses that control. Since he was created to be a divine being of "perfection", that loss of control is viewed as a mark against the "destiny" Astra has made for him. Because of this, he gets punished for it either by being harmed or being put in a situation where she gets harmed . Sylus is similar. He is an infernal being that exists to exploit weaknesses through desire, but since his power comes from the aether core in his eye that literally tempts people and then feeds off their desire when they indulge, he has to have control over himself or it will overwhelm him. He does that by indulging in them just enough. (Zayne does this as well with his sweet tooth) But he still has to be careful with how much he indulges and makes sure he keeps control, something that usually causes him pain, or he'll hurt her.
They were also both put in situations as children where they had no control and hurt her. Zayne as the Emissary, attacked he, and she landed in the hospital. Sylus would have been forced to kill her in the arena because he was older and his evol is more powerful, so he was forced to jump into the deep space tunnel with her to get away which landed her in a lab. Those were both situations they did not have control over. And those situations led to them becoming obsessed with control so they could be in her life again. Sylus has control through power and wealth and Zayne through self-discipline. This is interesting because they are both destined to harm her. The part of Zayne that is the Emissary of Astra sees her as an abomination and an anamoly that is dangerous. This part of him is always a danger to her and it has on many occasions hurt her. Regardless of his self-discipline, Zayne is still constantly afraid of hurting her, and will remove himself from her life if it means protecting her from harm. While she and Sylus are soulmates, they are Star-Crossed, they are destined to die with each other/destroy each other. Regardless of this, Sylus sought her out. I'm not saying Sylus wants to hurt her, I'm saying he's aware it's inevitable. And since the pain is inevitable, there's no reason to not be with her. Whereas Zayne is so afraid of hurting her that he will literally wipe his own memory of her, or even end his own life to make sure she's safe. Of course, this is all made harder by the fact that while they are these beings of extreme power, they were reincarnated into, and are bound by, human bodies. Also, both of their story lines and adult romantic relationships with MC start out cold and harsh, when you go down their storylines as love interest, they both develop the same type of warmth towards her.
Rafayel and Xavier are mirrors of each other as well. Their story lines are around the responsibility of leadership, agency, and sacrifice. The MC is literally a sacrifice to save their worlds, which they are the leaders of. In God of tides and abysswalker, Rafayel is aware he needs a sacrificial bride and at first, is accepting of it. He doesn't understand yet what it means to give her up because he accepts her as a sacrifice before he falls in love with her. When he's faced with actually having to do it, he can't. With Xavier, he falls in love with her before he is aware of people being sacrificed, So, when he becomes aware of it he understands fully and can't do it. Since they are both the leaders of their people, they decide to be the ones to make the decision on whether or not she'll be sacrificed. The problem is they don't tell her about it until it's literally down to the wire and everyone's going to die. They didn't give her any agency in the situation, so in their third myths, they deal with the pain of losing her because she chose to sacrifice herself because at that point there was no other choice. Xavier by coming home to Philos and finding out she had sacrificed herself to save the planet and Rafayel with literally being forced to allow her to stab herself in front of him through their bond. Because they are the leaders, they took the burden of the sacrifice on themselves and internalized it instead of explaining it to her and giving her agency. Even though a big part of their third myths was acknowledging that they had given leadership up to her, she was the ruler Romirro and she was the queen of Philos through her association with them, they still didn't tell her. They thought they were protecting her, but they just wound up tightening the noose. And after she is sacrificed in both of their stories. They become something much darker. Rafayel becomes the Abysswalker and Xavier becomes the King of Dark night.
They go down paths that they feel they have no choice in. It isn't until they're faced with the reality of her being sacrificed again that they finally break the cycle. Rafayel literally erased The Tome of the Sea God, and the entire fate of his people, so he's not bound by sacrificing her anymore and Xavier literally allows himself to die with her so they can go back in time and fix everything. And those myths go out of their way to point out that the most important factor was choice. Rafayel says the Lemurian's fate is in their hands, and after she's no longer tied to him, she still chooses to go back to him. In Xavier's myth the fact that she chose him over trying to pointlessly feed herself to the planet again is what gave her the ability to go back and fix everything. And I think it's the literal planet of Philos that points this out and thanks her for it.
That's my general analysis and I cannot wait to meet the 6th LI and find out who Caleb's mirror is.