In a sense, Sunny did what he did also for her. Why to be free of the Shadow Bond? Oh, to be free, yes. Sweet freedom. That's what he always repeated in his head, and that never changed. First, he grew stronger to be able to stand up to her in case she betrayed him. That was his freedom. Then he grew stronger to find his "convictions". That bound him to people, but in general it was also his freedom.
However Sunny being the most honest person in the world knew better than anyone to be suspicious of the truth. The truth is misleading, and can be used to manipulate people.So what happened then? He decided he wants the strength to be able to shape the world, right? Being bound by his own desires was his freedom. To be able to realize them was his freedom.Did he go against Nephis just because of his desires? Not at all! His desire bound him to her more. He even somewhat supported her in the Antarctica Campaign. He made his Shadow kill one of the Mordret's reflection, and together with Nephis he killed a Song's SaintBut again fate was so cruel to him. Instead of achieving what he wanted he witnessed one catastrophe after another, and in the end was forced to face his Third Nightmare, to become a Saint. And the Nightmare was just a loop of repeating madness.
He grew to despise his cruel fate even more. The Shadow Bond despite its apparent perks made him inferior to Nephis.He couldn't forgive Cassie for sacrificing him to fate. And then when the Nightmare was about to end she moved mountains just to offer him freedom. She warned him that freedom has a price, and that price was his bonds with friends.Despite that Sunny persisted. Even the future came to warn him. He persisted really hard. It was fate that bonded him with Nephis, but the same fate kept him from her. In the end to be with her he had to break this fate. Fate left only this one possibility. Fate is cruel, and so was Sunny. At the last moment Vile Thieving Bird ripped fate from the depths of his soul. Now he's fateless. He got what he wanted."I won... But did I? I guess I didn't."
Normally he would find his friends, and... celebrate the end of the Nightmare? Being alive is a good reason to celebrate. But it's not that simple. Fate is still cruel. Sunny learned this hard way. People he used to know don't recognize him.
Nephis, Cassie, Effie, Kai, Jet, and even Rain. He found them, but after meeting Nephis everything was clear. They don't remember him. How are they going to celebrate with him? At least they were good. Nephis and Cassie improved their position in the Valor clan being one step closer to destroying the clans. Jet, Effie, and Kai returned to the government, greatly empowering its forces.Then was Sunny..."What am I supposed to do now?"
Sunny could easily tell that there were plenty of things to do. He's a Saint, and has to master his new power so he can control his strength.
He has to find a place for himself to live. Being forgotten doesn't do anything good for his social standing.His home could be sold, and his Brilliant Emporium... without him it will bankrupt soon.On top of that he's banished from the Nightmare Spell. He can't access it, he lost many Memories, can't summon his runes, runes are not translated for him. Being a subject to the Nightmare Spell for years turned it into something pretty obvious.He cursed it sometimes, but it was also very convenient.Translation, displaying owned Memories, and enchantments, granting Memories, displaying the traits of his Shadows, instinct knowledge, descriptions of his attributes... He had to learn to live without it. While being banished from the Spell he lost most of his Memories.Only the ones that he created or modified remained. Without the Spell he won't be getting new memories for killing Nightmare Creatures."From now on it's going to be harder."