OttoKallen

OttoKallen is the het ship between Kallen and Otto from the Honkai fandom.

Canon
ELAN PALANTINUS

1465 the 13 years old Otto meets Kallen for the first time. His invention, a small airplane, flew over a wall. There it was found by Kallen and brought him back. Kallen praised his invention, which made Otto very happy. Because he was very ill and fragile, he was of little value to his family. Kallen was the person who first recognized him and his efforts. They became very good friends.

1466 the children were attacked by Honkai beasts. Kallen's father, Francis Kaslana, protected them with his life and died from burns of his weapon Shamash. It was then the first time Otto realized that if Kallen were to follow her father's path and become a Valkyrie of Schicksal, she would die the same way. This fear even haunted him into adulthood. After the death of Kallen's father, Otto sneaked into the Apocalpyse Reliquary to decipher the family relic. He was hoping to find a way to revive him. Also known as the Void Archieves, the Relict offers Otto to revive Francis in exchange for his life. When he brings Void Archieves to Kallen and explains the situation to her, she is anything but pleased. Instead of smiling again as he had hoped, she slaps him on the cheek. She explains to him that her father died to protect them both and that she doesn't want him to die for her (for her happiness). She then bursts into tears and Otto cries with her. They hug sadly.

1470 Kallen is already a Valkyrie of Schicksal. Her Kaslana oath is put to the test for the first time as her opponents are not Honkai beasts but humans. She decides to fight her opponent, the immortal warrier, but loses, because she lacks the necessary motivation. It is Otto who runs across the battlefield and stands protectively in front of Kallen. But her opponent let her live. Schicksal loses the war against Shenzou and Otto carry Kallen all the way back to the Schicksal Headquarter.

DORMITORY

1475 the Schicksal army was finally forced to retreat at the Kipchak Steppes in Central Asia. On their way back to Geneva, Kallen and Otto found a orphan, witch was struggeling for her survival. Kallen brought the girl to Europe and named her Vera. Even though Vera could never become a valkyrie, Otto took very good care of her. He taught her to read and write. He also ordered her a Valkyrie, which taught her how to fight anyway. Vera therefore regarded Otto as a kind of god and named himself "Octavia" after his favorite historical figure Octavius. 1543 she died peacefully in her sleep.

ELAN PALANTINUS

1470 a plague ruled the country, claiming thousands of victims. Otto tested a cure on the sick, which resulted in their death. As he spoke of "I must find a cure or she will leave me." and as he find the cure, saying: "I found it! She´ll never leave me now!" one can speculate that Kallen was meant and that she was also ill. Mainly because he cried afterwards. He says also that he can Kallen maybe happy with it.

Schicksals thirst for power had not paid off. Instead of being able to expand his claims to power, only the losses remained. To cover this, the church increased extra taxes in form of "Indulgences" to absolve their sins. As a result, people in west Europe became impoverished and began to hate Schicksal.

1476 Kallen and Otto take a little walk in western Europe, when Kallen bumps into a boy. The little boy loses his apples in the collision. Kallen immediately apologizes and wants to help him pick them up. But when he sees the brooch of fate on Kallen's robe, he runs away in panic and asks not to arrest him. In the background you can hear people whispering, complaining that Kallen took the apples from the boy. She then decides to look for the boy, but collapses briefly due to her wounds and is overthrown by Otto. Kallen wonders why people fear the church so much. Otto explains to her that fate punishes all those who did not take part in the war with fines in the form of indulgences. She wonders if these Indulgances aren't unjust before Otto invites her to dinner. After eating, the two become aware of a conversation between a woman and a priest. The woman asks him for more time to pay for the indulgences. But the priest demands her daughter Sasha as a tribute. Kallen intervenes and scolds the man. He tells her that he has to collect the money, because she lost the battle. Before the dispute can escalate, Otto intervenes. The priest then gives the woman three more days to pay the money and disappears. When Kallen gets upset that the man can just walk away at ease, Otto then tells her that vigilante justice is useless and that if someone hits her on the right cheek, she should also turn the left. then he tries to distract her by taking her to a show. On stage is a speaker who goes by the name of Shakespear and wears a mask. In a very poetic way, she denounces the Church. The show is interrupted by two guards who want to arrest her for slander. Kallen takes the dropped mask and a beach towel to disguise himself. Disguised, she grabs the speaker and takes her to safety from the guards. As thanks, Shakespear gives her the mask. Kallen, who no longer wanted to tolerate this injustice, and Otto hatched a plan to steal the priest's money and give it back to the townspeople. Otto provides her with outfits and the necessary equipment. They leave a letter for the priest announcing their break-in. But the priest was less concerned about the money than about the basement, which he immediately had sealed. The following night, with the help of Otto, Kallen, who had disguised himself as a young woman, managed to break into the priest's house. When she has packed the gold, however, she is asked by the priest and re-identified as Kallen. But she escapes through the window with the bag of money and gives the people their money back.

After Kallen has distributed the money to the residents after a secount night, she becomes aware of figures who are about to kidnap Sasha. Kallen wants to stop them. In their flight they lead her to the priest's house. Her path leads her into the basement, where she meets said priest, whom she captures and forces to open the door. She sees four girls attached to crosses and standing around a black box. In front of the black box is another cross that Sasha is hanging on. When Kallen demands the girls' release, the priest lies to her and tells her that they are meant to find a cure for the growing plague. When Kallen exposes the lie and tells him that for the cure are only needed some herbs and the girls aren't necessary for this, he tells her the truth. She learns that her friend Otto lied and instead using herbs for the first cure, sacrificed thousands of patients to create it. The priest also tells her that they want to use the cube as a weapon against their enemies in the east to take revenge for the lost war. Then three Valkyries enter the room. One of them is Eleanor Schariac, who was the first person who could heal Otto with his cure. Eleanor lunged at Kallen and wants to kill her, but is slowed down by Otto, witch was within the room and grabbed her spear to stop her from attacking. As a result, he injured his hand, which began to bleed. The spear's poison caused him to faint. Eventually, Kallen was taken away by two of the Valkyries and put in prison. Waking up after a nightmare about Kallen's death, his first route was to prison, where he briefly bumped into his father. When he left him alone with Kallen, he opened the door and entered the prison to talk to her. He tried to explain to her that if the cube could be used against the honkai and the sacrifice was necessary, it would secure the future of humanity. But Kallen, who had sworn to protect humanity, rejected this view. A conflict ensued which resulted from Otto's fear of seeing Kallen die and ended with Kallen slapping him across the face. Otto promises that he will make sure that she and the girl Sasha are released, but also says that he cannot stop the experiments. A little later the girl is brought to her and Kallen takes her home. In doing so, she realizes that Otto lied about the tests and that power reveals the true nature of humans. She then decides to follow her oath and act against Schicksal.

In Gun Girls Z 2 Era:ZERO Otto und Kallen are married in one timeline.

Quotes
"Otto… Do you still dream of making a flying machine?"

- Kallen

"To save the one and only her, I can only create new possibilities in the past. The other future will belong to her…"

- Otto

Fanon
OttoKallen is popular mostly in the Eastern fandom. The ship is mainly rivaled by SakuKallen and OttoWelt shippers. It's also common to see shippers enjoy this ship along with SakuKalpas.

The ship is beloved for it following the childhood friends to lovers trope and having one of the saddest story in Honkai fandom.

Some people draw parallels with KiaMei due to similarities of the two ships.

Trivia

 * In the official description of “Elan Palatinus” is "Year of our Lord 1470, Schicksal rallied the princes of Europe and unleashed a Crusade to conquer the Far East, only to be defeated by an immortal warrior. Kallen Kaslana, a powerful Valkyrie warrior, must make a choice between love and her oath". Since Yae Sakura was not mentioned in the manga, the sentence "to make a choice between love and duty" is about Otto.
 * In the box with the letter to Otto, Kallen Kaslana left two roses, which according to Chinese traditions are considered a sign of apology between lovers.
 * In “Thus Spoke Apocalypse” before little Otto and Kallen were shown sleeping by the tree, there were two bright stars, Altair and Vega. Old Chinese legend tells of the forbidden love story between the goddess Zhinü (symbolized by the star Vega) and the cowherd Niulang (symbolized by the star Altair).