Seeing Voltron Season 5, we all know the sequence of events that occurred within the growth of Lotor and Allura’s bond to one another. I did not trust him at first, but I knew from then that he had a secret motive. However, I knew some of the things he said to Allura in season 5 were indeed in fact, genuine, such as talking about their shared goals, Alfor and Honerva, and their time in Oriande. I would know this, because if you share something with someone, especially something that is very close to you, you tend to want to create a bond with this person, and share your fellow aspirations with them as well. That is the reason why he brought up so much regarding both their Altean heritage, and their goal for peace.
It is obvious that Lotor has taken fond of Allura. But did he truly care for her? Not as the Princess of Altea, or the daughter of the Alchemist King Alfor, but her as a person. Because almost each time from what we see, Lotor talks about Alfor and his [Lotor’s] goal for peace as a way to attract Allura. But from the way he brings the subject up, and from just… how he talks to her about it makes it look more like as though he was only using her as a tool to channel magic and help him build his ships. He shows his more vulnerable side to her, such through the words, “I cannot do this without you” as a sign of dependence, begging her to stay.
Their shared Altean history and future aim is what brought them together.
Despite having the same endgoal, their ways to approach it have different reasons, morals, and methods. As to which, separates them.
Allura is the Princess to Altea, an entire planet and civilization destroyed by mass genocide. She wants peace, and to stop the destroying of planets like her home had.
Lotor is the emperor to the Galra throne, who, also wants peace. As the new emperor of a powerful race, he would need all the power required to stabilize his empire that is, quintessence. He wanted to obtain that unlimited access to quintessence in hopes that on the day that he does acquire it, there would be no more disputes among the Galra, with the empire hopefully then becoming self-sufficient.
And to obtain that unlimited quintessence, he’d be willing to do and sacrifice anything to achieve his master plan.
After the destruction of the planet of Altea, Lotor did manage to find some remaining Alteans scattered throughout the galaxy. He indeed wanted to save them, with the intent of saving the Altean people and their culture through hiding them into his secret colony. However, he had to select “fit and worthy” Alteans to his so-called “other colony,” just to sacrifice and take their life force out of them to gain additional quintessence.
Once Allura found out the truth via Romelle, she was irate. The killing of other people, especially of her own race, is exactly what she does not want.
So when Lotor saw that Allura and the Paladins broke the gate to the unlimited quintessence, he attempts to negotiate with her. He begs her, with some panic in his voice. While still being civil, he states that his original plain of attain peace for the universe has never changed, and that they “are both on the same side.”
…But she can’t. Reminded by the destruction of her people, she says this:
Which leads to Lotor completely breaking down, attacking the Paladins and recklessly lashing out his intentions.
Both reminded each other of things they did not want to see and hear. At this point, I would not say that Lotor is entirely evil, but has a different set of motives and morals which are not entirely ethical. I’d want to point out that he, is quite similar to Loki. Not entirely evil, but hold their own personal plans for power– therefore being misunderstood. Simultaneously, he shares attributes with Zuko, being an antihero and most especially: Azula.
Lotor and Azula have almost similar reasons that lead to their psychological breakdown. They have gotten so close to their ultimate goal, only requiring one more step to obtain it. But as doing so at the brink of power and madness, they gradually fall apart in the process, leading to their forthcoming destruction.
In the end of their battle, Allura still showed care for Lotor by wanting to take him back to their reality. But at that point, the quintessence (or even the Dark Creatures of the rift) indicated that he was beyond saving in which he, most likely ended up like his own parents. It is unknown as of recent if he found some way to survive.
She had to make a choice. A sacrifice. Allura would have saved Lotor if she could, but that would mean for the quintessence and the Dark Creatures to consume all of Voltron as well.
Lotor has shown that he indeed loved her, and that he knew Allura felt the same. But was it worth the cost? Their similarities made hold for a better future. But their differences broke what they both desired to be.