#seyuna

seymour becomes obsessed with yuna very very very quickly, and chooses to marry her during operation mi'hen (as hinted by him telling yuna to take him as her 'pillar of strength' and referencing spira's most famous couple - zaon and yunalesca). now, he did not choose to execute his plan until three years before the game began, so this means he has seen many summoners come and go - but it was not until yuna crossed his path that he made his first move. 

seymour had to love yuna, whether you agree with the official ultimania plainly stating it or not, he had to because otherwise no bond would have formed and therefore his plan would not have succeeded. this is why he proposed to her in the first place - to try and kindle some kind of romantic feeling on her side and to get her alone so that their bond could develop. this is neither healthy nor pleasant, but its what was going on. and its even implied that in the end, his love for her went further than his plans and that he wanted to be sent by her. confusing, i know, but i'll talk about that another time. 

my point is, seymour fell in love with yuna so quickly and so obsessively, and i don't think this is a result of poor execution.

i think one way of interpreting this, one that i like, is that seymour saw his mother in yuna. 

seymour's mother had the largest impact on his character - after begging her not to sacrifice herself because he needed her and 'no one else', she did not listen and destroyed her own life regardless. though seymour did not use her for her intended purpose, her death permanently shaped his life. 

She, when he was a child, was his only hope. And she let herself be destroyed all for a idea that propagated false hope. He did not reclaim her as his aeon until he was twenty five, which shows that he rejected her incredible power. 

When the game gives you control of seymour, you cannot make him summon anima. in fact, there are only two known times when seymour uses her as his aeon - firstly, to beef up his reputation with the people of spira in luca, and secondly when he is defending his life. both instances can be interpreted as him obeying his mother's wishes, and both could be twisted in his head to mean he was doing what she wanted him to do. 

after all, anima sacrificed herself because there would be no way the people of spira would accept seymour otherwise, she said there would be "no other way." her whole identity and life had been about uniting the guado and humans under yevon, and it had failed and resulted in her son's revilement. her aeon is even shown strangling itself with an image of herself, further reinforcing that she died for her own image.

so, seymour using her in order to boost his own image fits perfectly. 

my point is, seymour probably still cared about his mother - at least to some extent. much of what he wished, such as an end to spira, can be interpreted as him wanting revenge for his mother's death. essentially, i argue that nearly everything about seymour is influenced by his mother.

except yuna.

so, if seymour saw his mother in yuna - it would explain why he became so quickly attached to her. and it would be cyclical - once again, everything would come back to his relationship with his mother.