Zed O'Brien

Zed O'Brien (ツェッド・オブライエン, Tseddo Oburaien) is a stern merman with powers similar to Zapp's as they were both taught by the same master. He is abandoned to Libra's care after his master approved of the organization's ability.

Appearance
As a merman, he has yellow eyes, blue skin with black markings adorning his head & wrist-blades that extend backwards like fins. He wears a black, sleeveless muscle-shirt, finger-less gloves & green cargo pants with metal sneakers. There is also a water breathing apparatus around his neck with a very sleek design, making them look like headphones.

Personality
A stark contrast to Zapp, Zed is a decidedly serious individual who has little patience for nonsense, particularly that of his fellow disciple. However, he's not above lashing back at Zapp, making it seem like he was okay with the sushi place Zapp picked out in order to mess with him only to reveal later that he disliked eating raw fish. This shows that he only said that to Zapp in order to fire back with his own brand of playful vengeance, knowing that Zapp wouldn't admit defeat and leading to the full events of Run! Lunch!! Run!!!. He is very polite and soft spoken though does tend to get annoyed when people laugh at him or try to insult him. He is also usually quiet and easy to get along with, going with the flow of events and tries to be agreeable. He is very well read, often seen reading books in his spare time due to the fact in the past his creator, an unknown count, talked with him a lot about poetry and music, art and science, philosophy, astronomy etc. In addition, he feels a strong sense of loneliness as he is the only one of his kind as he is a heteromorph who is half fish half human and is therefore not human but also not a creature from Hellsalem’s lot and as a result is rejected by both species. He does find friends within Libra and seems strongly connected to them, as he was looking forward to a New Year’s party to meet the other Libra members. He seems to be a loner, as he rarely hangs out with the other members except Leonardo, who often invites him to eat lunch and Zapp whom he often fights with.

Plot
Backstory.

Zed was made as a synthetic lifeform, half human and half fish (technically making him a merman). He was created by an unnamed count and both had numerous discussions about art, poetry, astronomy, sciences, etc. However, the count died by the hands of Raju Jugei Shizuyoshi. Zed was found afterwards by Master Raju, giving him a chance to live outside despite how alone his life will turn out to be.

Z's Longest Day.

Zed is first seen flying a stolen plane towards Hellsalem's Lot with the severed upper half of a Blood Breed Elder pinned to the nose using his blood.

Despite the strain of restraining the Elder while piloting for hours, he engages the Elder alongside Libra, only to collapse from shock and exhaustion after his Master abandons him.

Later, while recuperating in a specially prepared tank, to Zapp's amusement, he introduces himself to Leo and remarks how yesterday was the longest day he'd ever had.

'''Run! Lunch!! Run!!!'''

Leo invites Zapp and Zed out for lunch but Zapp insists on choosing locations specifically to try and mess with Zed, who calls him out on this more than once, all the while maintaining his cool attitude.

After Leo suffers a nervous breakdown, Zapp and Zed drag him to Vivian's diner, where, after checking to ensure nothing weird could happen, they prepare to dig in to a well-deserved meal.

Just as they are about to dig in, an armoured combat suit falls through the roof, forcing Zed to drag Vivian out of the way, tossing her clear but only managing to avoid being squashed along with the food thanks to Zapp's use of blood Threads.

After checking that Leo and the other patrons are ok, they are spotted by Klaus, who enlists Zapp and Zed to help him fend off the 1000 Yakuza brothers, who are rampaging through the city. In the end, exhausted to the point of becoming incomprehensible the trio stagger off to a Sushi bar. After Zapp ends up getting sick on some bad tuna, Zed later reveals at the hospital that he dislikes eating raw fish.

Power & Abilities
Big Dipper Blood Battle Style (斗流血法): Shinatobe branch of the Big Dipper Blood Battle Style, which is different from Zapp's. This allows him to manipulate his blood into tridents (in substitute from swords) or thread which he can then strengthen by channeling wind. This is called Big Dipper Blood Technique in the FUNimation dub.
 * Blade Form Five, Piercing Dragon Spear (刃身の伍·突龍槍): Unlike the Kagutsuchi, Zed's style creates a trident out of his solidified blood, which he occasionally tosses at an opponent with great force to attack from a distance.
 * Blade Form Two, Sky-Slicing Strands (刃身の式·空斬糸): After creating the Piercing Dragon Spear, Zed tosses it to a desired location then converts the trident into a web of string that ensnares the opponent
 * Heavenly Winged Bellows (天羽鞴): Zed creates a powerful whirlwind from his blood to further enhance his attacks and shred his opponents. This can also be used to further enhance the "Seventh Hell" technique.
 * Wind Knitting (風編み): Zed creates a 3 small vortexes within themselves to capture or release his enemies.
 * Crimson Orb-Weaver (紅絡新婦): A technique which the user creates a net made of blood.
 * Reverse Fish Bowl: Zed uses strands of his blood in order to suspend an orb of water over his head in order to breathe in case that his headphones are broken or stolen.

Trivia

 * Zed bears a resemblance to Abe from the Hellboy series.
 * A tweet from the Official Kekkai Sensen Twitter Account confirms that Zed's height is 176cm and his weight 58kg. It also is stated that his blood type is A.
 * Nightow mentioned in the Official Blood Blockade Battlefront Fanbook B5 that Zed is not a child, despite that his age is mentioned to be 13 in it. Since Zed was born on a leap day, his real age is evidently 52.
 * As the storyline advances, Zed seems to fit better in Hellsalem's Lot and become more emotive. This shows in the chapter "Angry Young Merman" where we see him lose his temper at the end.
 * Zed's favorite subject is health, while his least favorite subject is world history.