So I've come to decide that the reason I don't like Setsuna F. Seiei in these initial episodes of Gundam is as follows:
1st, and most irrational, he looks like Shinn Asuka. Thankfully, he's better behaved. But Shinn's design, which I once found cool, is pretty sullied by his memory.
2nd, and more concrete, he killed his own family. This sets him a great deal apart from Sousuke Sagara, whose mother died trying to save him, and whose comrades in the Mujhadein were slaughtered by Gauron. I don't feel any pity at all for Setsuna knowing he's gone and done this.
3rd, and most important on my list: while he behaves, to a certain extent, like Sagara and Heero Yuy, he doesn't talk like them at all. Sousuke was oblivious of everything other than killing, and it showed when he spoke in comical and endearing ways. Heero only spoke when he had to, and judging from flashbacks its because he'd been a right monster before hand. Setsuna, on the other hand, spouts the kind of garbage I expect I put into character's mouths when I was fifteen. "Why do you deserve to pilot a Gundam?" "Because I exist!" I mean, REALLY, he's so, so utterly melodramatic when he DOES talk.
He also will suffer the entire show from being compared to Sousuke, and will never get out of that shadow for me. This goes back up to the top in "irrational" since I've already said that child soldiers who know mean mercenaries isn't unique to FMP but I'll be damned if it isn't hard not to compare the two all the same.
All the same, Setsuna isn't the Gundam pilot I hate. I dislike him, but he, unlike Shinn, has the good sense to keep his mouth shut most of the time, so as not to rile me up. His being quiet does wonders for his character's standing in my eyes.
No, the Gundam pilot I despise for Gundam 00 is Teria or whatever the hell his name is. In addition to looking as much like a lady as possible, he acts like Quistis Trepe on steroids, and is such an entitled, self-righteous douchebag that I can't help but hope he betrays the group and dies in the process. Purple haired douchebag looks like a lady is what I call him in my head, and if this were Gundam AGE he'd have died by now.
In fact, the good news about Gundam AGE is that as long as the character you hate isn't named Asuno or Galette, they'll be dead in three episodes anyway.