The Blood Pact was formed and sustained through blood.
Although the Carmine Systems integrated into metallic mechs did not appear to serve any functional use, their symbolic and metaphysical functions were much more significant!
Blood was the medium that tied the Carmine mech pilot and Carmine mech together.
The choice of blood was deliberate. Due to swallowing a certain enlightenment fruit, Ves had become intimately familiar with the extraordinary properties of human blood.
Water and other liquid substances clearly weren't suitable. Ves might be able to circulate them through a Carmine System, but an active Carmine mech pilot would quickly get poisoned as a result!
Even if the mech pilot received heavy augmentation that enabled him to function with water flowing through his veins, it still wouldn't work as well.
