This proves Garp was very familiar with notorious pirates and Brook’s bounty meant Garp knew who he was. As evident in the case of Shakki, Chinjao and Roger, Garp has a proclivity to chase pirates he has an interest in. Chasing free the famed captain of the Rumbar Pirates is consistent with Garp’s character. Now in chapter 319 or episode 227 Kuzan said to Luffy “Your Grandpa helped me a long time ago”.
This could mean Garp inspired a wayward Kuzan into becoming a marine only possible if Garp must have had a special interest in Kuzan (his dad being a notorious pirate). This won’t be the only time Garp kept the secret of a pirate’s son. As in Ace’s case, clearly Garp understands that the sins of the father shouldn’t affect the son.
Kuzan idolizes Garp and in all probability, Garp adopted him (Kuzan’s childhood pictures depict abject poverty, a sign implying he was an orphan) like in Ace’s case although unlike Ace and Luffy, Garp had successfully turned him into a marine further aggravating Garp’s obsession and consequent heartbreak when he failed with both boys.
It could be that, Garp didn’t inspire Kuzan to become a marine but that Kuzan would have been denied joining the Navy if his father was a pirate. Although X Drake was not denied leading me to believe strongly in the former explanation. But then again, the fleet admiral was different in both cases implying different policies. Bottom line is, Kuzan owes Garp an unexplained debt; and that is the secret of Brook being Kuzan’s father.
*Theory by orogolden
