Originally, Nia was curious towards Shido, the person who helped her escape from DEM. As a result, she used <Rasiel> to set up their meeting and even agreed to go on a date with him out of gratitude. Still, she did not believe that he could get her to open up to him. However, Shido incurred her anger with his inaccurate cosplay of her favorite character, Tokiya, and violating her privacy through security cameras.
During their sales competition, Nia became frustrated when Shido pinpointed that her fear of invading others' privacy was preventing her from making friends, and was bewildered when Shido offered to befriend her even if she looked into his past. Eventually, after they tied in manga sales, she used <Rasiel> to peek into the other Spirits' pasts. She found herself understanding how Shido's honest personality was able to save the other Spirits. The bond developed between them during that short period of time was enough for Shido to successfully seal her and save her from certain death at the hands of DEM. Afterwards, she retains her gratitude towards him, though she still continues to mercilessly tease him at times. She shows interest in having Shido work for her after he graduates from high school.
Takajou-sensei is a fellow manga artist who was once Nia's friend. However, Nia distanced herself from her out of fear that she would eventually use <Rasiel> on her, This caused Takajou-sensei to believe that Nia hated her.
The two ended up meeting again during Comico, where Takajou-sensei bought a copy of the manga that Nia was selling. During their short time together, Takajou-sensei stated that even if Nia hated her, she will always enjoy reading the manga she had written. After recovering from having her Sephira Crystal stolen, Nia announced to Shido about her plans of reconciling her friendship with Takajou.
The AI of Fraxinus EX has a very condescending attitude toward Nia, going as far as calling her careless for losing most of her powers to Westcott. She remains scornful even when Nia gives her the capacity to physically manifest, but agreed to help her during the Spirit battle royale if Nia shares the reward of confessing to Shido. After gaining her own body with a Realizer, she occasionally helps Nia at her workplace in exchange for a salary, but also still relentlessly bosses her around during work hours.
Kurumi confronted Nia with the intent to make use of her Angel, <Rasiel>, to answer her questions about the First Spirit. Despite initially viewing Kurumi with caution due to knowing about her violent history, she still remarks that she is grateful to her for removing the security of the DEM ship transporting her. Despite saying that she won't give Kurumi any dangerous information, she ultimately relented and gave Kurumi the information about the First Spirit.
When Kurumi gained the ability to use <Rasiel> after she bonded with the stolen piece of her Sephira Crystal, like the other Spirits, Nia was shocked. However, she also made fun of it, comparing it to NTR. Kurumi, on the other hand, seems to openly enjoy mocking Nia over this, even flaunting her newly acquired <Rasiel> in front Nia on certain occasions.
Out of all of the other Spirits' past, Natsumi's story, in particular, resonated the most within Nia's heart, especially Natsumi's words of wanting to teach Nia how beautiful friendship can be. After Nia is sealed, she is impressed by Natsumi's drawing skills and approached Natsumi about the potential of working for her as an assistant.
During the Spirits' battle royale, Nia saw the opportunity to team up with Mukuro in order to use her wormholes to instantly transport her army of Marias to the locations of the other Spirits. However, the alliance was short lived thanks to Mukuro's growing guilt over using such a tactic.
Ellen was send to capture Nia alive after her existence was discovered by DEM, which she managed to do by catching her off guard through a sneak attack. Despite this though, Nia didn't seem too bothered by Ellen abducting her and later only playfully mentioned it to Shido, though this was while her memories of DEM's torture were repressed.
After Ellen lost her memories and joined <Ratatoskr>, the organization sent her to work as an assistant for Nia after the manga artist requested help for her approaching deadline. While Nia originally planned to be strict with Ellen due to her traumatic past involving DEM, she soon became increasing frustrated and enraged at how Ellen failed to perform any of the basic tasks for the job like erasing rough sketch marks. However, Nia still has some level of appreciation for Ellen's assistance, even covering her with a blanket after the Wizard collapsed from exhaustion after the manuscript was completed.
Nia was uncharacteristically hostile when she first met the founder of <Ratatoskr>, deeming him a hypocrite for wanting to save Spirits when he co-founded DEM and created the First Spirit alongside Westcott and Ellen for the sake of harnessing the power of the Spirits. However, she has not displayed any such vitriol since he admitted to his past deeds.