Natsuki Subaru[]
When they first met, Petra was suspicious of Subaru. However, when Subaru saved her from the Wolgrams, she was distraught by the condition that he was left in afterward. She also wished to apologize to him for being arrogant and causing him to have to save her. Subaru would accept her apology and treat her with the same kindness that he had shown her before. Thanks to this, she started to develop feelings for him.
Her feelings had grown to the point that she decided that she wanted to become a maid so that she could be closer to Subaru. She even went as far as asking the other girls of the village to not take on the position so that she could. Now, as an official maid and member of the Emilia Camp, she is doing her best to learn so that she won’t be a nuisance to Subaru and his friends.
She loves his kindness but also understands his hopelessness. Because of this, she would often be left frustrated with his actions. A primary example of this takes place in the beginning of Arc 6, where he had to break his promise to her in order to find a way to save victims of the Witch Cult. Though she understood and was against Subaru going to the Watchtower, she still saw him off and prayed for his safety.
Emilia[]
Petra recognized Emilia as the girl who would visit the village with Subaru and ended up fostering a good relationship with her. However, she also recognizes her as the girl that Subaru loves, so she finds herself jealous of her, attaching herself to Subaru and sticking her tongue out to Emilia on the way to the Royal Capital following Sloth’s defeat.
As one of the Mathers House maids, she is a member of the Emilia Camp, so she does her best to support the camp, learning the ways of a maid, politics, and even cultivating Yang Magic so that she might be of some help.
Frederica Baumann[]
Petra sees Frederica as her big sister. Frederica being her senior teaches Petra the basics of being a maid. Petra tries on outfits for Frederica and sleeps sometimes by her side. Knowing of Petra´s love for Subaru, Frederica supports her as she wants Petra to find happiness.
Roswaal L Mathers[]
Petra works at Roswaal's mansion as a maid. After the events of Arc 4, her relationship with Roswaal started to worsen. Her cheeks would stiffen, tears would force their way out, she'd deliberately spill tea on his lap, not taking out the pins of his clothes and she wouldn't tell him when his buttons weren't done up. Roswaal, on the other hand, doesn't dislike Petra, even standing up for her when she was accused of being the reason the mansion burnt down.
Ram[]
Petra respects Ram, being aware that she is actually the one in the mansion who can accomplish the most. She does disapprove of her slacking off though.
Rem[]
When the two first met, she quickly learned of Rem’s love for Subaru, and she deemed the Oni girl as a rival for his affection. However, she would end up forgetting her existence thanks to Gluttony.
Although Rem has woken up, albeit in a state where she has forgotten herself and has yet to be remembered by anyone else, the two have yet to interact again.
Beatrice[]
Petra sees Beatrice as her best friend and will do various things to take care of her.
Otto Suwen[]
Petra and Otto share a friendly relationship, and the two are often the ones most worried about the camp. Petra often teases Otto, but this is often in jest. In arc 7, Petra became frustrated with Otto for taking on more than he could handle when he was attempting to use his Divine Protection in the war efforts, so she stuck by his side and assisted him with her Yang Magic, telling him to rely on his friends, leaving Otto speechless and accepting her help. Later in Arc 8, she would punch Subaru in place of Otto when he was clearly frustrated with his concerns regarding Spica.
Meili Portroute[]
Petra thinks of Meili as a villain, not forgiving her for the things she did. But as a maid she still takes care of her, making her stuffed toys with Subaru.
Musica[]
During their travels to Vollachia, the Emilia Camp would find themselves in conflict with the mole people. Representing the camp, Petra placed an Oath Curse Mark on herself and swore an oath with Musica to let the mole people meet Emilia.