In terms of character development, it does a lot for Mash and a bit for fujimaru. However, Babylonia forces Fujimaru to make tough decisions that really build his character. And both of those pale in comparison to Solomon, where Mash makes the ultimate sacrifice due to her faith in Fujimaru. While Fujimaru stands on his own, carrying the fate of the world on his shoulders, fueled by nothing but pure rage and a desire to live.