Wei Yan

[Kuan P'ing]

I believe that the whole Wei Yan is traitor thing IN THE NOVEL is all just to glorify Zhuge Liang. At their second meeting (The first I believe Wei Yan helped Liu Bei, but then lost his trail to follow and join him) when Wei Yan killed his leader (Han Xuan?) Zhuge Liang's first word's were to kill him because he had an "aura of defiance". Bu Liu Bei stepped in and saved his life. Then later when Wei Yan "disobeys" orders, a general (Ma Dai?) is sent to kill him.

[Wizardman]

I do believe Wei Yan was loyal to Shu. Keep in mind that he nearly joined Liu Bei before he even had any land, back when Wei Yan was with Liu Biao. Henever found him, so he joined Han Xuan. When Liu Bei invaded, Wei Yan did betray Han Xuan, yes, but wasn't that becasue he was loyal to Liu Bei? Zhuge Liang saw "defiance" in Wei Yan, but you're going to see defaince in anyone who joins you after they killed their ruler. At the same time, if Wei Yan was a traitor, why did he do what he was told during the entire Nanman campaign? After Zhuge died, he made one of his only mistakes in giving instruction to Ma Dai and Yang Yi to kill Wei Yan. When Wei Yan rebelled in the end after Kongming's death, it was a setup. However, this setup did show that Wei Yan bad a bit of defaince left over from 25 years ago (Jing campaign), and that he could betray Shu in the long run.

What this shows is that he was loyal to LIU BEI. Was he loyal to Kongming? perhaps. But to anyone else? of course not. He slew Han Xuan, deserted Liu Biao, and "betrayed" Liu Shan.
However, notice how none of those rulers were all that good.

[LiuBeiwasGreat]

In the end Wei Yan was loyal but too arrogent. He committed treason and therefore is a traitor. While Yang Yi was scumy and really got himself in trouble later on was technicly in charge of the army and Wei Yan could not accept that he wasn't chosen to lead the army and just did something incredibly stupid and paid the price. Too bad because he was the best Shu Han had to offer at the time. Things might have gone diffrently for Shu Han if Wei Yan had lived.

[White Horse General]

He slew Han Xuan, deserted Liu Biao, and "betrayed" Liu Shan.
However, notice how none of those rulers were all that good.

Just because the ruler isn't very good, that doesn't justify treason. He could have left and joined another lord, Zhang Liao did it several times without having to attack his former lord or his interests.