Al

Aldebaran (アルデバラン), commonly known as Al (アル), is a member of the Priscilla Camp and plays the role of Priscilla Barielle's knight. Though he only has supporting roles in Arc 3 and Arc 5, he is a supporting character in Arc 7.

Introduced in Arc 3 as Priscilla's constantly abused knight, it is quickly revealed that there might be more to him, following the revelation that, like Subaru, Al was summoned to the new world from Japan roughly 18 years ago. His air of mystery only increases in Arc 5 as he is revealed to be familiar with both the Witch Cult and the Witches of Sin.

Appearance
Al stands at five feet and seven inches tall, making him the same height as Natsuki Subaru. When meeting Subaru for the first time, Al was around forty years of age. His frame is stocky and his body is covered in thick bulging muscles that give him an imposing impression. After an unfortunate incident in the Empire of Vollachia soon after his arrival about 18 years before the start of the main series, Al lost his left arm from his forearm down. Instead of resorting to a prosthetic limb, Al has the stub where his forearm used to be covered in bandages. There are various other scars scattered across his body, including a pair of claw-like marks on his right forearm and a vast assortment of scars on his face that left him disfigured. His overall shabby look, including his clothes and unshaven legs, make him look like a bandit or some other kind of lowlife. It could be said that his appearance is the polar opposite of his mistress, Priscilla Barielle.

Every piece of clothing Al wears gives a slightly different impression. His ensemble consists of a pair of green split-toe sandals with yellow buckles, sand-colored linen trousers, a bandage around his right wrist that matched the one that goes around his missing limb, bandages of the same assortment that are wrapped around his feet like socks, an open green linen vest with yellow lining and a hem of white fur, and a shabby yellow mantle that reaches down to his hips. Additionally, he wears a brown belt with a golden buckle that has a collection of green pouches attached to it with his Blue Dragon Sword usually sheathed nearby. His most defining physical quality is the pitch-black helmet he uses to conceal his scarred face. The helmet in question, in contrast to the rest of his clothing, is very refined and features a plume of neat red hair as a crest. Contrary to how he seemingly presents himself, Subaru believes that the way Al chooses to dress serves as a means to hide his true feelings and intentions.

Under his helmet, Al has long black hair wrapped in a ponytail, black eyes, and a stubble beard. He wears the same outfit as before even when regressed to his younger self during the events of Arc 7, but instead of his helmet, he uses torn-up wrappings to cover most of his face, similarly to how Vincent first appeared at the start of the Arc. From the visible parts of his eyes, he appears to have sanpaku, with small irises that make the whites of his eyes stand out. Additionally, he has long, black hair that appears to have purple strands and is tied up in a messy ponytail.

Personality
Al has a frivolous and goofy personality, and having spent more than ten years in a different world, he was easily able to get along with Subaru. Despite being Priscilla's knight, he doesn't really recognize himself as one, seeing himself as her caretaker, while Priscilla herself sees him as a handyman and a jester to entertain her. He has no qualms about their relationship. He also brags that the only way he can fight is by outwitting people and catching them by surprise. Though he acts aloof, Al somewhat cares about his appearance, as he demonstrated insecurity regarding his disfigured face several times. He adores the helmet that he wears on his head, as he feels that he wouldn't be able to have face-to-face conversations without it. Because of his light-hearted tone and friendly disposition, Al is a man who is easy to get along with even when taking his eccentric behaviour into consideration.

Although very skilled at fighting due to the time he spent in Vollachia, Al does not like to make enemies, as he considers that taking care of them when a problem occurs requires a lot of work, though Priscilla doesn't seem to care about this. When he does fight, Al is excessively calculative and patient, yet he additionally expresses frustration with his opponents on occasion.

Despite his easygoing attitude, Al has a dark air to him as noted by Rem. He holds immense rage towards those who wrong the people he cares about while not hesitating in bringing death to those who he fights. Though his off-putting behaviour and tendency to keep secrets is noticed by Priscilla and Rem, his suspicious activities even caught attention from the Sin Archbishop of Lust, who pointed out Al's secretiveness and shadowy actions. Also, he is deeply affected by having a form of amnesia. Until he met Subaru, he sometimes had episodes where he would think of himself as losing the plot due to the memories he had from Earth. It's unknown how Al's amnesia came to be.

History
Al was summoned to the different world roughly 18 years before Subaru. At some point in time, he was trapped on the Gladiator Island Ginunhive in the Vollachian Empire as a gladiator and received a sword to battle as a gladiator with. However, while being trapped there, he lost his left arm in an unknown battle. He spent nearly a decade there as a gladiator fighting in the Colosseum until one day one of the gaolers let him escape because they could see that his eyes were full of purpose, unlike the other gladiators. To help him fund his journey out of Vollachia the gaoler gifted him his trademark black helmet which was made in the image of the helmet worn by one of the Colosseum's heroes.

Sometime later, Al joined Priscilla's knight tournament, an event with around fifty people participating, but failed to win. However Priscilla decided to choose him as her knight instead of the top 4 contestants.

Al is apparently acquainted with the holder of a Witch Factor other than Capella, as he told her that she was considerably "different from the Sin he knew". He also is in some way acquainted with the Witch Cult and the Witches of Sin, as he knew that Typhon died in Priestella, where her remains resided, was in possession of a Conversation Mirror connected to the Witch Cult, and he also knew about the Authority of Gluttony's effects.

In The Sword Wolf of the Scintillating Flame, Al states that silver hair brings him bad memories about how a "trash, stupid useless person he is" due to how he failed to be of any use and to protect the one he cherishes the most. He was saved on the verge of death by Arakiya, who was then later saved from The Gladiator Empress by Al in return. He stated how he changed Arakiya's fate by saving her, and then reflected that the world may receive a big change if she were to get children in the future. As he thought this could be one of the marks he had left on the world, he then mentioned that he would get shouted by his "sensei" if he were to say it out loud.

Abilities
Unknown Authority (権能 Ken'nō): Al has been shown to possess a yet-unnamed and unexplained ability which he himself calls an Authority. In order to activate it, Al must meet unknown criteria. Once activated, space-time warps around Al, creating a range of sorts. Within it, the Authority is active and can take effect. Whenever Al or the target dies within it while the Authority is active, time within the area will reset back to a point in the past. He describes it as a metaphorical coin flip which decides the "role" he plays while using his Authority, though he seemingly can not control which "role" he gets. He also suggests that the area of a location is important in activating it, as he needs to "wrap" it within a certain area. On at least one occasion, Al has referred to his ability as a domain (領域, Ryōiki).
 * If Al is the "Victim" (被害者, Higaisha), he will be able to remember previous loops in his domain while his opponent will not. This ability functions as something eerily similar to Return by Death, with the two notable differences being that he has the advantage of him being able to choose a checkpoint and the disadvantage of it not being automatic. There doesn't seem to be a limit to how many times he can die like this, as he died to Priscilla a thousand times trying to convince her not to go to the Empire of Vollachia.
 * If Al is the "Aggressor" (加害者, Kagaisha), his opponent will remember the previous loops while he will not. His opponent is then trapped in a never-ending loop of trying to kill Al, seemingly unable to escape until they lose their minds. Al will be unaware of his deaths and can just deactivate the ability almost as soon as he casts it, as, from his perspective, his opponent went instantly insane. This was demonstrated in The Day I Gave Up on Being a Following Star.
 * It should be noted that if the Authority is broken (how this can be done is unclear), if Al chooses to deactivate it, or if he leaves its range, he becomes vulnerable once again, as said in his fight against Capella Emerada Lugunica during Arc 5.

Magic User (魔法使い Maho Tsukai): Al is able to use Earth Magic.
 * Dona (ドーナ): Al can summon one earth wall, which is used as a defensive spell.
 * El Dona (エル・ドーナ): Al conjures a swarm of earth mana and pinpoints it at the body of a target, usually channeled through a medium, which then the effected area bursts into spikes from the inside out and expands outward. This magic was cut from the Light Novel.

Equipment: Al owns a liyuedao and wears a black helmet which he received when he was at Gladiator Island Ginunhive. His helmet is a replica of a helmet once associated with the Gladiator King.

Trivia

 * According to the author, Al is involved with one of the three mysteries of Re:Zero, and revealing his circumstances would answer it.
 * Al's full name, Aldebaran, is the same name as the brightest star in the Taurus constellation. It means "The Follower", as the star appears to "follow" the Pleiades, which is also located in Taurus. However, he does not like being referred to by his full name.
 * The reason why Al denies being a knight is because he absolutely hates knights.
 * On April 12, 2020, Al's voice actor Keiji Fujiwara passed away due to cancer.
 * Al stated he is fond of silver haired girls, just like Subaru.
 * According to Garfiel, Al and Subaru have similar scents.