Kassius is a stern, by the book, no-nonsense officer. He is loyal to the Empire and happily works for Sidious' agents. He is shown to be considerably more intelligent and competent than Aresko and Grint and far quicker on the uptake than either one as shown when he realizes that the Rebels are trying to mask their escape with decoy devices and when he advises Kallus to allow a orbital bombardment. However, he's not as insightful and as blessed with foresight as the Grand Inquisitor, Darth Vader, and Grand Admiral Thrawn, because as Governor Arihnda Pyrce states "he is more of a politician than soldier". He is also aware that the Empire uses decimation. He's also shown to favor brute force attacks and other power type tactics
However, Kassius is also shown to be self-serving as shown when he voices the intention to blame a subordinate for zapping Vader's ship with a tractor beam by mistake. Furthermore, he does not seem view any of his colleagues as friends, even Agent Kallus despite agreeing with the ISB agent a lot as he shows no concern for him when he returns injured from a mission. He's also shown to not take the Rebels seriously and when his failures against them finally outweighed his successes against the lost Jedi he became increasingly thirsty for glory which became his downfall.
Role in the Series
Admiral Konstantine played a minor role in the first season. He was mostly seen taking orders from the Grand Inquisitor. He was later seen evacuating Grand Moff Tarkin during the destruction of his ship, while the Grand Inquisitor perished in the battle.
His first major role was in the second season premiere. He was the commander of the blockade over Lothal. When multiple signals that match that of an Imperial shuttle that the Ghost cell stole appeared, Konstantine instantly realized that the Rebels were trying to mask their escape and ordered TIEs to shoot all that matched the signal down. But the Rebels still escaped. When he reports it to Darth Vader, Vader ordered his ship prepared. Confused, Konstatine asked Agent Kallus what's going on and Kallus told him that the ship the Rebels stole had a tracker on it. When he arrived in the system the Rebels were tracked to, Vader ordered the Admiral to take the Ghost cell alive. Konstantine ordered the tractor beam's activation, but instead of the Rebels it caught Vader's ship by mistake.
Sometime later, Konstantine and Kallus receive a report from Clone Commander Wolffe that the Rebels they seek are with him. The pair dispatch a probe droid to the area that confirms the report as true. After arriving in the system, Konstantine suggested using orbital bombardment but Kallus took three AT-ATs downplanet to fight them. Suddenly, the Admiral receives a message from Darth Vader to rendeveau with his shuttle and took the fleet to the destination. Upon arrival, Konstantine was surprised to see the Fifth Brother, who revealed that Vader dispatched him to assume leadership of the hunt for the Rebels. When Konstantine protested that they probably made Kallus lose his fight with the Rebels, the Inquisitor declared that he didn't care for his struggles and would succeed where he and Kallus had failed.
Konstantine held a low esteem towards the Fifth Brother due to his reliance on imprecise information and his lone wolf approach. When a officer reported a power surge at an abandoned medical station, Kallus and Konstantine both dismissed it but the Fifth Brother confirmed it was the Rebels and went alone to nab them. He later came back with the Seventh Sister, who Konstantine held in higher esteem. When the Seventh Sister's probe droid revealed that the Rebels were on Garel, Konstatine dismissed this possibility because he was sure they would've got a report about it by that time. However, Kallus confirmed the Inquisitors' report correct and ordered him to deploy a Fleet for Garel.
Six months after the demise of both the Fifth Brother and the Seventh Sister on Malachor, He and Agent Kallus had resumed the hunt for the Rebel Network. He and Kallus were visited by Grand Moff Wilhulf Tarkin. Tarkin informed him that Governor Pryce was coming with the Seventh Fleet to assume command of the hunt for the Rebel Network which she feels was become a galaxy-wide threat to the Empire. Konstantine dismissed Pryce's theory stating his belief that she was overestimating how well organized the Rebels were. He also adds that the Rebel Network is just pockets of resistance not a galaxy-wide operation. Suddenly, Pryce arrives with Grand Admrial Thrawn, the Commander of the Seventh Fleet. The Chiss tells Konstantine that he agrees with Pryce's theory and vows to stop the Rebellion. Later, they get a call from Commander Brom Titus who tells them the Rebels are attacking Requim Station and go there. When Thrawn contacts them, Pryce informs him of the Rebel Fleet's arrival only for him to tell her that's not the Rebel Fleet and tells them to let them go. Surprised, Konstantine tells Pryce he doesn't understand why they're letting them go and Pryce tells him it's because she and Thrawn are after more than the capture of one Rebel Cell.
During his time under Thrawn's command, Konstantine become increasingly aware of the fact that because of everything that's happened since the death of his late boss the Grand Inquisitor he is no longer held in high esteem by higher ranking Imperialists such as Arihnda Pryce as Thrawn increasingly assigns him missions where his only job is to cut off the Rebels and make sure they don't escape and becomes increasingly determined to regain respect and favor from Emperor Palpatine and Imperial High Command. When Thrawn finally locates Chopper Base and attacks it, he places Konstantine in an Imperial Intecector and and orders him to keep the Rebel ships from making a jump. When Jun Sato pulls his ship forward, Konstantine orders his ship to intercept it and ignores Thrawn's orders to return to position. Suddenly, Sato's ship swings toward him with the intention to ram the Interceptor so Ezra Brider can make a jump. Realizing his mistake, Konstantine orders an evasion but is too late and he and his crew perish when Sato's ship rams his.
- The admiral shares his name with two prominent Romans: Cassius and Constantine. This is ironic since this pair are both his exact opposites. Cassius was a Republican and Constantine was religious.