PersonalityJinbei is a Fishman with great pride and honor. He is known to the World Government as a pirate-hating pirate, possibly due to the actions of the pirates in Fishman Island, kidnapping Fishmen and Merfolks to sell them as slaves. However, he has a soft spot for Whitebeard and his crew as he sees them as a completely different story. Because of what Whitebeard had done for his homeland, Fishman Island, he understands the damage a war between the World Government and Whitebeard would cause. He knows that places like his home, which are protected by simply belonging to Whitebeard's territory, would suffer the most from the war should Whitebeard lose.
Despite being proud, Jinbei appears to put his priorities and principles over his honor, and is not above retreating from an otherwise unfinished battle (even being shamed or openly mocked by an opponent) if it meant for the sake of the greater good. He also doesn't seem to hesitate from the idea of encouraging others to do likewise for a similar cause, as seen when he pleaded and managed to convince Luffy to prioritize Ace's safety first over avenging his brother's loss against Blackbeard. Jinbei has also displayed great humility regarding his personal strength and status; a trait most unique among the Shichibukai. This was made apparent by his willingness to even lose the said status for his refusal to fight against the Whitebeard Pirates.
Portgas D. AceJinbei and Ace were once enemies (since the latter wanted to kill Whitebeard), and nearly killed each other in a fight that lasted five days. Despite this, the two respect each other deeply and Jinbei is determined to help Ace's brother Luffy rescue him. He also has a high respect for Ace's captain, Whitebeard. Whitebeard claimed Fishman Island as his territory and, in doing so, saved it from the World Government and other pirate attacks. For this, Jinbei refused to participate in the war against Whitebeard, even if it meant losing his Shichibukai title and being imprisoned in Impel Down.
Monkey D. LuffyHe seems to be quite impressed by Luffy's recklessness of breaking into Impel Down in an attempt to save just one life (Ace's), a feat that not even Whitebeard has done. This makes him one of the very few pirates outside of Whitebeard's crew whom Jinbei respects. His respect for Luffy grew as they made their way out of Impel Down to save Ace in Marineford. He also seems to feel gratitude and guilt for Luffy's defeat of Arlong, (possibly because he was the one who dispatched Arlong into the East Blue in the first place).
WhitebeardThough no interaction has been shown between the two, Jinbei has expressed many times that he owes a great deal of gratitude to the Yonkou for his protection of Fishman Island. As for Whitebeard himself, the Yonkou appears to have developed a sense of tolerance towards Jimbei, despite the fishman's Shichibukai status (Jimbei has even implied that he visits Whitebeard and his crew from time to time). Over the years, Jinbei's respect has grown to the point where he will readily declare himself as adversary to anyone or anything with ill intent upon the Yonkou's life, which is why he immediately engaged in battle against Ace on their first encounter, since Ace was out to assassinate Whitebeard at that time
ShichibukaiAmong his fellow Shichibukai, Jinbei seems to have some sort of history with his former peer Crocodile and is noticeably upset upon realizing Crocodile is incarcerated in the cell adjacent his own.
According to Hannyabal, despite the title of Shichibukai bestowed upon them, Jinbei had never personally met Boa Hancock prior to her visiting him and Ace at Impel Down. He was rather displeased with her at first, thinking she came to mock Ace, and that he distrusted her when she told them that Luffy was in the prison to save Ace. It is unknown what he thinks of her after realizing that she told the truth and in heat of battle, she attacked Comodore Smoker to protect Luffy and openly stating that Luffy is her beloved.
He also seems to be familiar with the newest Shichibukai, Blackbeard, probably back in the days when Blackbeard, as Marshall D. Teach (as he was then known), was still a member of Whitebeard's crew under 2nd Division Commander Ace. Currently, Jinbei is furious with Blackbeard for Ace's incarceration and impending execution. At the same time, Jinbei seems to respect Blackbeard as a formidable opponent. He briefly warned Luffy of Teach's history when he was still part of Whitebeard's crew, saying he was an individual who must not be antagonized recklessly.
Sunny PiratesIt is unknown what his relationship with the Sunny Pirates was like, but upon his entrance to the ranks of Shichibukai, the crew was disbanded and split into smaller factions. It is also unknown what his former equal, Arlong, thought of him. However, Jinbei seemed to feel guilty of releasing Arlong into the East Blue.
Abilities and PowersJinbei is a master of Fishman Karate, which he can use to knock away many guards at once. His strikes are so strong that he doesn't even need to make physical contact with a person as the very air will blow them away. Another example is that he defeated Minorhinoceros, one of the four Demon Guards, with a single uppercut, while Luffy used his Gear Third to defeat another Demon Guard.
Jinbei also appears to be quite swift, even on dry land, in contrast to his large size. He could intercept an enraged Luffy (in Gear Second mode) and prevent him from further assaulting Blackbeard.
Though strong, he admitted himself that he is of no use on land battles, implying he is much stronger at sea. In Chapter 546, Jinbei stands up to this claim when he lifted one of Impel Down's massive entrance doors and used it as a raft to provide passage over the sea for Crocodile, Mr. 1, and Buggy (all Devil Fruit users), with himself acting as the raft's propeller underneath. He not only managed to pursue the fleeing battleships, but even outmaneuvered the incoming cannonballs fired at them by the Marines with relative ease. This allowed the trio to board one of the Marine ships sailing away from the Gaol. He also displays being able to manipulate water as if it were a tangible cloth through Fishman Karate and Fishman Jujitsu, even using it to attack from a distance.
It is stated that he was able to battle Portgas D. Ace as his equal. They both nearly killed each other in a five-day long fight just before Ace was taken in by Whitebeard. It is unknown if they're still equal in power.
He and Arlong were once said to be equals, though whether it regards to their strength or status is yet unknown.
Also, he is one of the few people to be able to take a "baptizing" in boiling water in Impel Down without flinching, which is considered an impressive feat. On top of this, he shared the same cell as Fire Fist Ace, who is considered one of the most important prisoners in the world at the moment.
Aside from his immense strength, Jinbei has also shown the ability to communicate with fish, even at a long distance. He summoned a large school of whale sharks to the Calm Belt (which was usually too dangerous, with the Sea Kings infesting it) to assist him in a mass-breakout of Impel Down. The ability to speak with fishes is usually unique to merfolks, so Jinbei's capability to do so is to be noted.
He is also a capable helmsman, shown when he steered the stolen Marines battleship.
From his demonstration of underwater activity, it is obvious that he does not have the powers of a Devil Fruit. Even at one point cursing the weakness of Devil Fruit users as he saved them from drowning.