Patroklos Alexander is the son of Sophitia and Rothion Alexander, the younger brother of Pyrrha, the nephew of Cassandra Alexandra and Lucius, and the grandson of Achelous and Nike. When a mysterious customer gave Rothion a peculiar metallic fragment, the household went out of control, with the children fighting violently over what their father just received, while Sophitia was experiencing an aftermath from her previous wounds she sustained in her first battle against Soul Edge.
Awhile after her younger sister, Cassandra, set off on her quest, Sophitia made her decision to get involved in order to save her children. When she arrived at Nightmare's former stronghold, she had an encounter with a green clad girl, who wanted to 'play' with her children. Upon returning home, Sophitia found them safe, for now. The girl in green met up with her again, saying that she would be back for them when the time is right. Sophitia knew that she had to stop her, especially with both Pyrrha and Patroklos' lives at stake.
Tira returned to the Alexandra household in her ending in Soulcalibur III, where (in her default ending) she entered Patroklos and Pyrrha's bedroom and started to talk with them. Tira's intention was for Soul Edge to choose a new host out of the two children (it presumably chose Pyrrha due to the fact that she was kidnapped by Tira and became Pyrrha Ω in Soulcalibur V).
Patroklos had been raised by his father, Rothion. Rothion would convey stories about Sophitia and her holy mission to destroy Soul Edge. Patroklos, as a result, desired to become a holy warrior, just like his mother and to one day meet her.
When he was fifteen years old, Patroklos won a sword-fighting tournament, but that same night, his father began to succumb to his illness. Before his death, Rothion told Patroklos the truth about their family. Sophitia was killed in battle by a group of malfested and Patroklos' sister had been abducted by a malfested wielding a ring blade. Patroklos vowed to rescue his sister and avenge his mother. After years of training under several masters of the fighting arts, including Setsuka, he learned of Graf Dumas' recruitment for warriors to hunt down the malfested. Patroklos chose to work under Graf Dumas in hopes of destroying the malfested.