Alpha Centauri is an augmented human who is the leader of a very powerful galactic government known as the Rapture Federation and been so for a long time. She wasn't always a leader, matter in fact she used to be a "regular" human that fought against the machines back in her homeworld. But eventually the machines(known now as the Rapturian) won the war that led to genocide of humanity, however she along with two other humans were chosen to be augmented. Such augmentation stop her aging process and increase both her physical and mental strength and gave her robotic arms, but completely lost both her identity and humanity.
Alpha along with her new brother and sister, Omega and Proxima, led the Rapturian people into a new age of discovery and colonization. However, such early history since the foundation of the federation was a dark chapter which ultimately led the deaths of Omega and Proxima. Such deaths had a profound influence on Alpha that led to a doctrine of conquest and war against any lifeform that oppose the federation.
Alpha as leader could be describe as smart and strong, rarely showing any compassion to those who question her authority, and ruthless when it comes to battle, but she is honorable against an opponent... that is why she has a lot of enemies, with little friends. But regardless the Rapture people admire her accomplishments of uniting and protecting their massive federation from centuries of wars and crisis and that of peace and prosperity. But those who are close to her, they know that underneath that hard, cold shell she is very compassionate and caring...which includes also been a mother to an adoptive daughter. She deeply cares of her people in the federation, even if it means making hard choices just to keep them save from the dark forces that looms in the shadows.