He didn't dare define it as an identity crisis, he didn't dare admit to himself that there was a possibility that he was anything less (or more) than human. He didn't dare begin to entertain the notion that his inability to relate, his inability to empathize, his inability to articulate exactly what emotions he was feeling was due to some disconnect between himself and the rest of the human race. The fact that emotions were so hard for him to define was surely a result of simply being goal oriented. Any personal want or need or goal was secondary to the needs to Celestial Being. He was not an individual, but simply a part of a greater whole – a part of something greater than himself and it didn't matter that in some way, personally, he was unfulfilled and unexplored. His own needs were secondary to the needs of the world. Sacrifices must be made.
That was what it was, a sacrifice, he told himself. A sacrifice of personal understanding. Of course he didn't understand Allelujah's bleeding heart mentality and he didn't understand Setsuna's personal and spiritual devotion to the Mobile Suit. But more than anything, he did not understand Lockon's empathy. An empathy and understanding the extended to every member of the crew, regardless of position. Of course Tieria lorded himself over others, he was the only one able to access Veda, he was the crux of their entire operation. They would be adrift any helpless without his ability to interface. In addition to this, he was a Gundam Meister. It was not a title given to just anyone, to any recruit that came to Celestial Being with a mind for the cause, it was something you earned. Tieria's understanding of hierarchical social groups simply lead him to believe that he was to be revered for his services. It wasn't that he truly understood why, or believed himself to be superior – it was simply his understanding of human social interaction.
But it spiraled out of control. He found himself feeling so far removed from his crew mates, as though despite any of their efforts (which simply was giving the rest of the crew the benefit of the doubt – the only other member of Celestial Being that ever took the time to truly involve him in matters outside of missions was Lockon) to include him in social interaction he found himself dismissing the entire thing as petty and meaningless. The reality of it was his attempts to belong in an emotionally bonded, and dare he say, familial social group, felt artificial. That any attempts to relate, to understand his own emotional reasoning were simply futile. His longstanding assumption that he was necessary and revered slowly began to ebb away, slowly began to turn to a feeling of inadequacy as those around him began to give up on him.
There was much of human emotion he didn't understand, but he understood why he found himself alone. He was difficult, he was distant and cold. But it was only because he didn't understand those around him. He didn't understand Christina's dogged optimism despite the collapse of modern society as they knew it. He didn't understand Feldt's love for parents who had long since passed.
He didn't understand love.
He didn't understand the need to put the life of another before your own – it went against everything he understood about self preservation. He didn't understand the notion that someone could "complete you" (he had heard Christina use the phrase in the past and found himself lingering on the notion for far longer than he would have cared to admit), insinuating that a human being was somehow incomplete and the faults and flaws of another could somehow negate and better the flaws of the self. It wasn't as thought humans existed in a state of incompletion. The human concept of self was self contained and individualistic. He understood that humans paired off, and often times it was sensationalized as something more than mere brain chemistry and science at work, but the notion of love was completely lost on him. The notion of love was strictly a human concept, invented to explain away a perfectly simple chemical reaction. It was simply a fallacy invented to explain away character flaws. He didn't understand it, and found it to be a childish and delusionally optimistic notion.
He was so far removed from the understandings of his comrades. It was then he realized, it was not them who were childish and deluded. It was he that was missing some crucial piece of understanding. The rest, even Setsuna – who Tieria found to be the most reasonable, had an unspoken bond. An unspoken understanding that Tieria simply lacked. It was a sacrifice, he began to tell himself. A personal sacrifice. To remain distant was to protect the rest of them. It was only natural that one by one they would die for their cause – it was unrealistic to think otherwise. To become attached would be to open oneself up for weakness. He was setting an example he could only hope the rest would understand.
Of course it was all for naught. Of course a personal breakthrough must occur at the time of resignation to the norm. Of course he would be personally invested in Lockon Stratos. He understood this compulsion even less than he understood any number of perfectly routine interactions. He didn't understand his need to be near him, to have his actions validated by his comrade. The opinions of others never phased him, or mattered, but it was a compulsion to be approved of by this man. He hated the notion of Lockon participation in mission because of Tieria's long accepted concept of mortality. He hated that Lockon was frequently sent to Earth. He hated the planet that had caused him so much trouble, but wanted to understand it because of Lockon's concept of "home". He couldn't make sense of it. He didn't understand it. Home was arbitrary, it wasn't a universally accepted concept, it was simply a domicile that one had feelings of nostalgia for – what sort of fondness could be had for a planet that was destroying itself? Every logical part of his brain understood his contempt for Earth, and yet he found himself, more and more, offering to return to the planet with Lockon. As Tieria's pshyche became fragile, he found himself more and more returning to his comrade. Never really showing signs of weakness or affection – any indication that his actions were out of admiration – simply a compulsion to be near the man.
More and more, Tieria's dogmatic view of the world began to come down around him, he was separate from humanity in so many ways. He had the potential to understand social groupings, to understand human emotion. But it was Lockon, more than anything, he wished to understand.