For this theory to be true we need to dig into what Ohara was about and what might have been the drive for Kuzan. We know that Ohara was this “demonic” island in the eyes of the World Government that practiced forbidden studies on history of the World.
Ohara were aware of this fact and thus they isolated themselves and they tried to protect the sholars. This went well for years…decades…centuries, but then the World Government finally eradicated Ohara from existence. The Buster Call happened.
Looking back, this could have been a scenario that could have been foreseen. Ohara learned alot about the life of the world’s ancestors, they researched history refering to the Void Century and the Ancient Kingdom. I think Ohara was aware of informations about how the world kept the balance back then and how it was broken. A sensible spot indeed. And thus Ohara has been a viable target for the World Government.
If I am correct, then Kuzan as child has been told stories about an ancient justice and this could have inspired his way. He became strong, and he became a marine in order to protect the secrets of Ohara and have them be passed onto future generations.
We all remember the secene where Saul confronted Kuzan and they had their exchange about justice and the Buster Call.
What is fascinating is that according to my theory Kuzan had to play a role and supress his past to keep his undercover role as navy. As if he were a real ex civillian of Ohara then he would like to help in this situation but he can’t because of his duty as vice-admiral. This is proving the fact that Saul was the opposite. He deflected his position as Vice Admiral. Him doing this foreshadows another possible hint I will come to later.
But to prove this we can find one critical scene where Kuzan is out of his usual character…a so called “Character Break”.
It was shown when Sakazuki’s ship attacked evacuation ships. So the fact Kuzan was in his character was because there were actually evacuation ships saving citizen. If he himself couldn’t stop the Buster Call, he could easily have people escape. This happened because Sakazuki is forming the opposing, the antagonistic force and justice to Ohara. The Absolute Justice opposed Ohara and Kuzan has a moment of share with Ohara here. This is the biggest foreshadowing to the fact that Kuzan’s justice is possibly belonging to Ohara and their studies. Kuzan having this emotional character break sides him with Ohara.
Later on he took out Saul, he somehow spares him an even more brutal death and he saves Nico Robin. Something he will never regret. Only by the time he might figure out his true success.
So this foreshadows us the Character Arc’s essence, about failing and success.
Kuzan failed to save Ohara, he failed to take down Akainu, he also spare the Straw Hats, in a metaphorical way he failed his marine duty. When will his success come?
By this time he must have the will to take revenge for what happens, and this could be his biggest motivational trigger to oppose Akainu. Akainu’s misdecision, Ohara’s destruction, wrong justice in lead. It is tied together aswell, same as the reasons for Ohara’s downfall, the same reasons can be found in Kuzan’s character.