The Fujimaru twins weren't the only masters that the servants within Chaldea Had. There was a third who appeared in the middle of the seven Singuarlites from a different timeline from theirs. The 3rd master gained self-worth and matured greatly among the twins. Went through the Epic of Remnants and unfortunately like with the Fujimaru twins forced to become...(Full summary inside)

As Shirou rotted in his cell, he was offered a chance. A chance to be free from a life of nothing but imprisonment. A chance to life his life without regrets. A chance to see his sister again... Of course, in order to obtain such freedom, he had to save another world. Irony could be pretty cruel sometimes.

Bonus series of adventure that Nagumo can find and propose still in the fateverse. Who knows? Maybe he could find treasures, heroes, myth and fun when doing it? (Rated M for short interventions and innuendos)

He finished concquering the great Labirynth by himself, imagine his surprise when he is adopted? as he wondering where he was ? Imagine more surprsie when he recalled things he didn't do in the other world. Embark on the adventure for the grail. (A arifureta x fate/zero crossover just for your and my enjoyment.) (M rating for obvious reason as of chapter 12). Anyway, Enjoyyy !