
At first glance, he seems like a cold hearted and strict person. He does not smile nor show much emotions. His emotionless personality is probably due to the fact that he is noble so he feels superior from everyone else. He believes that it is his responsibility as a noble to be a perfect role model for the rest of the shinigami, therefore his devotion in following the rules are high. There are a view occasions though where he is out of character, such as marrying Hisana and adopting Rukia which he considers an execption
2 days later, Rukia's trial was being held at the Sokokyu hill ,Byakuya goes to attend it.But before the exection can be carried out Ichigo intervenes once again ,this time pushing back the Sokokyu and destroying the frame that holds rukia in place both of which have a power of a million zanpakuto's ,Byakuya then fights Ichigo to prevent him as well as his sister from escaping from the hill alive, through a series of flash steps ;Byakuya comes to understand that Ichigo has become a bit moire powerful so he decides to release his Zanpakuto's Shikai (Initial Release) ,but after much irritation due to Ichigo's constant questioning of Byakuya to release his Bankai; Byakuya goes ahead and uses it, Ichigo tries to dodge the senbonzakura kageyoshi but can't keep up with it's speed and gets hurt real bad , Ichigo then releses his own bankai , After a few minutes of fighting it becomes apparent to Byakuya that it is impossible for him to win like this,so he uses his Bankai's second form ,Senkei Senbonzakura Kageyoshi (Scene of a massacre). This form does not affect Byakuya's speed but removes all the defensive power that the original form of his bankai had.
Later on ,after the events of Aizen and the other traitors are relesed to the public ,Byakuya shows up on the Sokokyu hill to save rukia ,preventing her from getting killed ,but instead takes the sword aimed at her unto himself.After Aizen and the other traitors leave to Hueco Mundo ,Byakuya apologizes to Rukia for not having tried to save her and tells her all about why she was taken into the Kuchiki clan (this was due to Hisana's dying wishes), he also explains that twice before he had broken the Kuchiku family rules by marrying Rukia's sister (Hisana) and by letting Rukia enter the Kuchiki clan. After he had broken these two rules he had promised on his parents graves that he would never again break the family rules.