Betrayal

Archer's betrayal of Rin to join Caster. Don't say it was just so he could defeat Caster, it was only so he could accomplish his goal of killing Shirou.

When Rossiu had Simon imprisoned in TTGL and subsequently got a lot of people killed. It wasn't surprising but it really made me hate him even more than I already did. When they showed him crying my hate was alleviated a little, but he still sucks. I was really glad he wasn't a part of the fight with the Anti-Spiral. He would have just been a huge downer and they probably would have died.

Herlock tells Tadashi Daiba that he was the one that killed his father ,at his father's request, he then tells him that Tadashi must kill him to follow what he set out to do or herlock would kill him for not being a man of his word. They don't show the outcome but its a very interesting idea. Not really a betrayl because herlock tells him to shot him and we don't know if he even does , but it is the one that sticks out the most for me along these lines.

Ritsuka finds out that not only is his brother Seimei still alive, but his brother was the one who tatoo'd the word 'Beloved' on Soubi's neck and discarded him as a slave. Not only that, but he has been killing other masters and slaves and is willing to do anything to reach his goals, even fight against Ritsuka.

Gut's best and life long friend betrays him and all his friends and family to sell all their souls to hell to become king. Everyone was brutally slaughtered and or eaten besides Guts who lost and eye and an arm only to see his only love be beaten and raped by his best friend Griffith (who sold their souls before that)

Aizen betrayal was epic. It was just epic. So unexpected.

During the flashback, when Tomoe ultimately betrays the shogunate that sent her to assassinate Kenshin, cumulating in her death and pretty much set up everything that would then happen in the main story

I think it's worth noting that he didn't actually manage to penetrate her, and the guy was so messed up it was pretty pitiful.

Fucking Kaaya and Neeba betrays the entire group and leaves Jil behind like a leftover. Why bother betraying Jil if Kaaya still had feelings for him? Stupid stupid stupid. Made me rage so bad that I still haven't had the gumption to finish the second series.

He was betrayed by his master who used the command spell telling Lancer to kill himself, just because the master was stupid enough to be tricked to do so.

I mean they worked together respected each other and won Saber: YAY Kiritsugu: I use my last command spell to command you to destroy it..