ye shall be as man
He wakes up. He fights. He draws access to sources of power that scare him, that should scare anyone with half a brain. He meets a girl, and he comes to understand that he must protect her - but that she, also, must protect him. That she must come to terms with herself, and the places in her that liken to gaps only others can fill; that the fact of being human and the feather-light weight of a life are things that must be shared. Must be taken, as much as they are given.
He understands. It takes time and trials and tribulations and pain, but eventually he understands. He's got no choice but to. Everyone's depending on him, even as they all come to understand themselves that they can't only depend on each other.
That as the world makes demands of you, you must reflect your own desires back on the world. Do you see? It's frustrating, I know.
Noah can't remember, has never known, a time before war. This may be colloquial stretching of the truths everyone in Keves and Agnus hold oh so definitely not dear (but for the fact that you cling to any routine you're offered, among relentless turbulence), but it's still true, in the end. What does it matter what you remember if you were born at the age of ten? Your experience has been preemptively rendered expendable.
Fei, meanwhile, does quite literally have no memory of a time before peace. He was...in some sense engineered that way, after all. He's left the village, but it will always be his origin point. And he is not expendable. Unlike Ramsus, he is one of the most important beings in the universe. But how was he to know? No one knew, truly, what he would do until he grew up.
And when you grow up, you have to accept responsibility. For your actions, for others around you, for your future...
For your memories, from the first to the last.