Why did Kuzan join the Blackbeard Pirates?
We know he hasn’t all of a sudden turned evil, we are told as much in his conversation with Smoker.
When they are all drinking at the bar, Catarina Devon suggests he might have information about the missing Red Poneglyph. Laffitte shares some intel about the “man marked by flames” and Shiryu mentions it might be in the hands of the World Government.
None of the Blackbeards mention Ohara… However, the next panel Kuzan connects the conversation to Ohara and Jaguar D. Saul.
At first he immediately refused to join, but given some time he reconsidered. Clearly he thinks he can use the Blackbeards to achieve his goal.
His goal likely traces back to Ohara and Jaguar D. Saul. Kuzan had long been tormented by internal conflict and awaited Robin’s answer.
The events at Enies Lobby finally provided the answer he sought.
His internal conflict has been resolved, the lazy justice gone, he’s now a determined man on a mission.