Cyrus betrays Caulder and assists Will in locating his secret stronghold. Claulder kills him for it.
Cyrus is determined to prove his humanity to Caulder by acting of his own free will. He is sick of being treated as a worthless mindless clone, and tries to prove his humanity to his "father." He seems to feel lonely as evidenced by his comments to Will when Lin comes to back him up.
Cyrus doesn't seem to have any meaningful relationships other than his defining enmity with Caulder.