The final offense
Disclaimer: I don't own any of these characters but they own my emotions. These stories are the effects of my post-Thor: The Dark World viewing. Enjoy and do let me know what you think.
Loki collected his resentments like a greedy dragon hoarding gold.
He believed they were all he had left, all he could hold onto. Without his anger, he would have nothing.
There was much he resented about Thor and Odin, the latter especially. All the lies he had grown up believing, all the illusions he had been surrounded with, the future that had been teased to him but had been ultimately denied him.
He would never forgive the All-Father. He blamed him for ruining his life, for pushing him towards the twisted path from which he could never return. He wanted someone to blame for his suffering even if a part of him knew that some of his deepest wounds were self-inflicted.
But there was one grudge that surpassed all the others, the spark that fuelled a rage that made him forget his past anger; that overshadowed a life of accumulated minor resentments; it was Odin's utter neglect, not of him, but of Frigga.
Because Loki knew Odin well and he had seen how often he would forget about his queen and get engrossed in his kingly duties. He remembered how often she had been set aside because the king had other matters to attend to, though not always so urgent.
Frigga had understood Loki so well because she knew all too well what it was like to watch from the sidelines, to be overcast by the radiance of her husband and king even when she was the force that kept the family together all those years. She who would break up fights between Thor and Loki, who would intervene when Odin let his pride and rage get the better of him. She was the voice of reason in a home full of warring egos and bellowed assertions of might and authority.
Odin said he did not involve her in some crucial decisions in order to protect her, to keep her safe.
"But where were you when Malekith and his monster drove a dagger through her heart? The one time she truly needed your protection?" Loki thought bitterly, "Off chasing shadows and taking the bait like fools."
And she died protecting you, protecting the world, preventing the enemy from acquiring his deadly weapon.
She died keeping you safe, as she always had.
And you failed her, as you always have.
The one time you could have truly saved her, the only time she needed you, you were not there.
That, Loki could never, ever forgive.
No sorrow, no repentance, no remorse on Odin's part could ever make amends. There was nothing he could do to fill the void Frigga had left behind. She was lost to them forever.
Odin knows this. And for once, he is even willing to accept Loki's loathing. Because he can offer to rebuttal to Loki's arguments, no defense against the accusations laid at his door.
This time, it was he who stood guilty before a judge just as harsh as he had always been.
Frigga was the only one who could have convinced either of them to relent and show mercy.
But Frigga was gone.