So the main reason the fused monster are lacking certain features is that the three of them who transformed are actually blind, mute, and deaf. And here I thought they are here due to the reason for killing two of its companions. I was wrong since they seemed to be compatible with each other especially since they cover their weaknesses with each other.
And I also think I already knew the main reason why they are currently like this and have fused to each other already. Since they needed to be together, they wanted to fuse themselves together and form a complete being. But because we have interrupted the fusion process, their fusion process ended up in a disaster, forming their abomination-looking form.
