The kingdom of Asgard is a mighty one, striking wonder in the heart of all beings worthy of experiencing its majesty. The water it towers over is crystal clear and reflects the stars' glimmers brilliantly. The castle itself is crafted with such diligence and skill that it virtually glows with power. The architecture is art, the nature divine, the atmosphere invigorating. And none could attest to this fact better than the young princes that spent their days reveling in their home's beauty.
As children they'd raced through the gardens of Frigga, slowing to admire her most treasured plants. They stopped to smell the flowers and climb the trees, embracing their opportunity to explore as the children they were but with patience, as father taught. They walked the fields and tumbled down the hills that surrounded the massive city. They wrestled to display their strength, puffing their chests out and growling menacingly to appear tough. Thor tackled Loki, but fell to the ground empty-handed and confused. Loki ran up giggling with giddiness at tricking his older brother with his magic. They fell into the grass snickering and sprawling, pointing out the pictures in clouds they saw. Odin and his wife sighed happily at the boys' innocence. With the responsibilities they'd eventually need to uphold, it'd be best to raise them to strive for the throne. The All-father was reluctant to see his sons mature and become warriors when they were so youthful and sweet but as heirs to the throne it was imperative to begin their training as soon as possible. He was already teaching them about the role and honor of a king, a true leader. He saw the kings each boy could become. Thor would rely upon direct solutions, strength and power. He would engage war in a heartbeat and defend his kingdom at any cost, a valuable yet dangerous attribute. Loki, on the other hand, would be patient. Clever beyond measure and sly as a fox but less forthright. He'd be the leader to finesse a strategy methodically. It wasn't exactly a case of brawn versus brain because they both possessed both, but Odin realized that it would require his utmost effort to raise a fully competent king.
Loki always felt overshadowed by his older brother. It angered him. He was certain that their father favored the fairer prince. When Thor was deemed king, his choleric frustration was unmatched. He was smarter, stronger, better! ... or so he believed. The god of mischief felt betrayed. He couldn't let his family decide his fate like this, he deserved that throne! So he betrayed them. Loki attacked his own home and stole from his own family. Endangered his friends and damaged his home. He thought it just. They didn't deserve him, he could rule any realm he set his sights on! He convinced himself that he hated his father, his brother. But when he was dangling off of the Bifrost Bridge, his scepter gripped by his "brother", gripped by his "father", he realized that they were his family; after all of the strife he caused, they still reached to save his life. All he wanted was to be accepted, recognized. So he called up to Odin, pleading. "I did it for you, Father! For all of us!" He searched that all-seeing eye for any hint of sympathy, of forgiveness, of love. But he found a somber frown, despondent regret. "No, Loki." His fears were confirmed. Odin had rejected him, spoken those words full of disappointment. That was what stung most. He had failed his father. And with one final helpless glance at his beloved brother and life-long friend, and a hardly choked back sob, he let go. He not only released his desperate hold onto family, but also life. He didn't care anymore if they did not accept him. Because they were all he wanted, and now all that he could do in retaliation was hurt them in every way possible. He'd destroy Thor's beloved Midgard, rule and slaughter its population and further disgrace Odin.
He disowned them, denying the acknowledgement of his brother and father. He abandoned them as they had him and struck back with a fearful vengeance and force tenfold.
But he could never hurt them as much as they had him.