Christopher's failure [failing his parents]

They never expected their sons would achieve one part of their dreams, but utterly shatter the other.

Christopher never saw his brother at their parent's funeral. Calling him didn't work until many years later when the first "evolved" group that came out after the Dark Age was in a critical situation.

Since many people had metal replacements and A. I that could take over their bodies only to save their lives, they became the first force in the early stage of the Dark Age, known as cyborgs but to the horror of the entire federation.

A massive cyber holding robust enough to face the federation head-on suddenly controlled over 72% of the cyborgs, turning them against the federation.

It was a disaster as their bargain was to split which the federation vehemently denied, to divide in a period when they were supposed to be together against the night beast was a big no to the higher-ups.