well, lets go back to the LWW. He gets into this magical world, where he is made High King over all the other kings besides Aslan. And then, he leaves, after 15 years of being High King, and he is upset because he was king, and now he's just a kid, and thats all people will ever know him as. He is frustrated and wants to be king again. Thats why he gets into those fights (he obviously got into more than just one), because he obviously feels that people should respect him as a king, but they, as I have already said, only see him as a boy. And then, he gets back to Narnia, and he is better at first, because he is back where he feels that he belongs, and he is high king again and even when Trumkin doesn't believe that they could be the kings and queens of old, he calmly lets Edmund prove to Trumkin that they are who they say they are. He then learns about Caspian, and, I think, doesn't want Caspian to be king, especially after the Castle Raid. I think that Josh is right though in that the whole time, he is only doing what he thinks is best for Narnia; as High King, that was and is always what he has and does want, the best for Narnia. The Castle Raid would have been a success if Caspian had stuck to the plan and, after he didn't, if Peter had tried to call it off, I mean, they probably would have figured out a way to alert their troops and those infiltrating the castle of the danger. Then, the castle raid goes wrong, yet he keeps going, because, 1. It could still work, 2. I think his pride may have gotten in the way a little bit, 3. I think that he needed to prove to HIMSELF that he's still high king and that "he's still got it" if you know what I mean. He realizes that Caspian may or may not be the best choice for the new king of Narnia and when the White Witch is almost brought back, he is ready to stop her from coming back, again showing he wants what's best for Narnia, and after pushing Caspian out of that circle, is enchanted himself by the witch. He couldn't do anything about it, and though he should have known better, he listened to her, until Edmund stepped in. He changes completely after that. He does the duel with Miraz, RISKING HIS OWN LIFE SO OTHERS DON'T HAVE TO DIE and so that his sisters can try to find Aslan. He doesn't want to die, saying to edmund worriedly "What do you think happens back home, if you die here?" He is willing to die, but would rather not. One of my favorites of his lines is, after Miraz asks him if he is to cowardly to take a life, says "Its not mine to take." He is ready to let Caspian do it, showing that he has accepted Caspian, and that he is making a complete turnaround. And finally, in the end, he even gives Caspian his sword, a sign of his complete change, and says that he won't need it anymore. He doesn't seem bothered that he will never return to Narnia, and in fact, seems to accept it rather well.
Thats just my opinion. I think there was SOME pride involved. I don't think that he was a jerk at all, and actually, I probably would have behaved in a similar way! I mean, I'm the oldest in my family, well technicaly not, I have 3 stepsisters and my mom and stepdad (my dad died of cancer 2 years ago) but I still feel like the oldest kid in the family. I know that if I suddenly gained a ton more responsibility and then, after being so used to it, lost it all, gained it again,and find that I may not have it for very long, I would be the same as him. I think he is more realistic this way, as this is how many people would have reacted.