Why not just....
Solidus and Liquid work together? Since both of them hate and want to destroy the Patriots. As for Solid Snake well he can't join them because of some self-righteousness and Liquid doesn't like him him because he got all th dominant genes. I don't get it, Together they would've been unstoppable. What you people think?
"My clone brothers and I are called monsters, replicates of evil genes. You are one-of-a-kind... but still a monster shaped by a dark and secret history. We need to decide which monstrosity will have the privilege of survival" - Solidus Snake