He's not going to give the book back nor is he going to allow anyone else to find it. He'll put it back eventually when time presents itself for a better opportunity. Right now, he was more focused on Papryus and not allowing him to touch it again. It's tucked under his arm with the other book placed there concerning a Heart.

It's an odd take on it but Papryus is right. It made him into something horrid and there was no turning back from there. Suman was long gone by the time Allen had pulled him out. Separation from Innocence was never a good thing. "Maybe," he responds with the agreed disapproval that he would prefer Innocence destroyed instead of salvaged, "The only problem with that is that Innocence is never chosen. It chooses you, whether you want it or not."

Innocence was cruel. It didn't matter how much someone fought it or synced with it. Death was the likely outcome of an Exorcist's life. "Once it chooses you, it is only a matter of time until the news gets out somehow. A story of a boy with a strange ball on their head. A man with an odd arm. It hits the newspapers, spreads from country to country. Then it reaches the Black Order. It doesn't matter if you are young, old, a child, two years old. They will collect you and you will never see or know anything other than fighting again."