Otto Suwen/Relationships

Oslo Suwen
Oslo is Otto's older brother. Although Oslo believes that Otto has the ability to be a merchant, he also believes that he is someone destined to get in trouble wherever he goes.

In the past, when Otto had still not developed the ability to speak and had hearing problems caused by his divine protection, Oslo noticed that written communication was possible and thus taught Otto how to write. In turn, Otto viewed Oslo in high regard, always asking for his advice before asking anyone else.

Regin Suwen
Regin is Otto's younger brother. Otto and Regin are shown to trust each other deeply. However, Regin often worries about his brother's wellbeing, believing him to be naturally unlucky. Regin sees Otto as the person who inspired him to become a veterinarian.

In the past, Regin used to often demand Otto's attention, to which Otto reacted by indulging him. Regin was also the one who gave away the secret of Otto's blessing, when he once overheard him speaking with a Ground Dragon.

Otto is aware of Regin's feelings towards Marone, and is pretty supportive of their relationship.

Frufoo
Otto knows Frufoo since his childhood. Otto has a strong affection for Frufoo, considering her a friend and a member of his family. Although she sees Otto as a troublesome person, Frufoo is completely loyal to him.

Natsuki Subaru
Despite seeing Subaru as a problematic person, Otto starts considering Subaru as his friend during the events that take place at the Sanctuary. Otto is willing to help him out whenever possible. Multiple times Otto has even sacrificed himself for Subaru and his friends, although he claims he only looks at profit and losses, he cares for Subaru. This is demonstrated after freeing Subaru who was kidnapped by Garfiel, after which Otto consols him and tells him he came to save him because he's his friend. He then sacrificed his life to save Subaru from Garfiel. He consoles him yet again after Subaru's discussion with Roswaal, and then puts his life on the line once more for him during the battle against Garfiel in the Battle of the Lost Forest of Cremaldi.

Marone Lisbon
Marone and Otto are friends. Otto is very fond of Marone and sees her as an admirably strong person.

Emilia
Even before becoming an official member of her camp, Otto identified with Emilia's circumstances and decided to support her for the Royal Selection. The two currently have a friendly relationship. Otto usually gives her advice, which Emilia appreciates. She thinks of Otto as a very dependable person.

Garfiel Tinsel
When the two first met, Garfiel was hostile towards Otto, calling him names such as "third rate" because Garfiel didn't consider Ottos name worth remembering. During the battle of the lost woods of Cremaldi, Otto surprised Garfiel with his fighting capabilities, to which he apologises saying he had looked down on him, but now understands he's serious. After the events of the fourth arc, Garfiel gradually took a liking to Otto, and the two currently have a brotherly relationship. Otto tends to unconsciously indulge Garfiel because of the similarities he sees between Garfiel and Regin in his younger years.

Frederica Baumann
Frederica and Otto have a friendly relationship. They consider each other highly reliable people, and the two are shown to share their concerns about Garfiel as sibling figures.

Ram
Ram constantly teases Otto, but the two get along well, and Otto seems to enjoy her company. Ram actually thinks of Otto as someone reliable.

Ricardo Welkin
Back when Otto was captured and taken prisoner by the Witch Cult, Ricardo was the one who saved him from certain death. After Otto finally grasped the situation and started crying, Ricardo gave him a white handkerchief and turned around in order to give Otto some privacy. Because of that nice gesture, Otto feels somewhat indebted to Ricardo, swearing to himself that he'll one day repay the debt to him.