Batman is the vigilante protector of Gotham City, the patriarch of the Batman Family. Having witnessed the murder of his parents as a boy, he began a crusade against crime in Gotham as its "Dark Knight". One of the world's greatest detectives and most practiced crimefighters, with a plan or gadget for the most unthinkable of problems, he is known for his strict code against lethal force and large cast of allies. In this AU, he is the King of Gotham Kingdom, and he is a mermaid with a dark grey and black tail, scales, and fins.

Richard Grayson is the adoptive son of Bruce Wayne. Trained by the Dark Knight himself, Grayson eventually became Batman's sidekick, the first Robin. Afterwards, he graduated to the role of Nightwing. In this AU, he is the Crown Prince of Gotham Kingdom, who is charge of theater and the arts, and is a mermaid with a bright vibrant blue tail, scales, and fins.

Jason Todd is Red Hood, a vigilante anti-hero who is a member of the Batman Family and the Outlaws. Jason became the second Robin after Richard Grayson became Nightwing. Jason was trained by Bruce, and was his ward and partner until his death at the hands of the Joker. He was resurrected by Talia al Ghul using the Lazarus Pit. In this AU, he is the Second Prince of Gotham Kingdom, who mostly works as a mercenary, and is a mermaid with a dark crimson and ebony tail, scales and fins, which also have a subtle green tint at times due to the effects of the Pit.

Tim Drake is Bruce Wayne's third adopted son and the third Robin, becoming Robin after the death of Jason Todd. After being replaced as Robin by Damian Wayne, Tim became the vigilante Red Robin. In this AU, he is the Third Prince of Gotham Kingdom, and is in charge of the Royal Archives, and is a mermaid with a warm orange and red tail, scales, and fins.

Damian Wayne is the son of Batman and Talia al Ghul. He is the fifth vigilante known as Robin and operates as Batman's primary crime fighting partner. In this AU, he is the Fourth Prince of Gotham Kingdom, and technically, the second in line to the throne (unless Guest creates an exception), and is the head of military and defense at a young age. He is a mermaid with an elegant dark green tail, scales, and fins.

Duke Thomas is The Signal, the teenage metahuman vigilante and daylight protector of Gotham. His parents lost of their sanity due to the Joker. Eventually, Duke was offered to train under Batman and join his family officially. Duke is the Fifth Prince of Gotham Kingdom, who is in charge of grassroot communities and movements, especially with the youth. He is a mermaid with a bright yellow and ebony tail, scales, and fins.

Cassandra Cain is one of the world's greatest martial artists, and a vigilante of the Bat Family. She was trained to be the perfect assassin. Eventually, she was adopted by Batman and became Batgirl after Barbara Gordon. In this AU, Cassandra Cain is the First Princess of Gotham Kingdom, and is Damian's second in command, having her own elite force of guards. She is a mermaid with a dark violet and ebony tail, scales, and fins.

Stephanie Brown is a street vigilante who operates in Gotham City as a member of the Batman Family and the Batgirls. She succeeded Tim Drake and became Robin before being fired. Afterwards, she once more became Spoiler. In this AU, she is the Second Princess of Gotham Kingdom, and is charge of directing programs that help troubled teens avoid the criminal justice system, working with Duke a lot. She is a mermaid with a beautiful light purple tail, scales, and fins.

Barbara Gordon is both the Gotham City vigilante known as Batgirl and the computer hacker known as the Oracle, though she mostly goes by Oracle due to getting paralysed from the waist down. She is the daughter of Commissioner James Gordon. In this AU, she is the King's second advisor, and is the daughter of the Captain of the Kingdom Guard, James Gordon. She is a mermaid with an elegant lilac-periwinkle tail, scales, and fins.

Alfred Pennyworth is the polite, kind, and loyal butler to the Wayne family. After the Waynes' demise, Alfred continued to raise Bruce who later became Batman. He assists Bruce, and acts as a father figure to him, and the Bat Family. In this AU, Alfred is the main advisor to the King, and raised him when Bruce's parents were murdered. He is a mermaid with an elegant light grey tail, scales, and fins.