"Neptune is very kind or possibly super mean and hates us. But that's okay. She's really funny. Neptune looks in no way like she's supposed to be here. But that's why she's here, of course."
Neptune is bossy and fashionable, and doesn't care what others might think of her or how her own actions might affect others. Neptune typically behaves as she would like to, with little regard for others' approval. While she can be nice to those she cares about, her tone comes off as rather abrasive and sarcastic most of the time.
Neptune does genuinely care for Jupiter and Venus; however, her ways of showing it are somewhat unconventional. Rather than outright declaring it, she demonstrates her feelings towards her friends in more typically aggressive speech and actions, such as threatening to hit Jupiter if she doesn't stop blaming herself.
Neptune is close with Jupiter, but is angered by Jupiter's attempts at being "good." She thinks that the ways Jupiter doesn't let anything hurt her are unnatural and messed up, and wishes that Jupiter would be able to react more strongly towards people's attempts to hurt her.
Neptune also has a desire of a certain extent to protect Jupiter, and fears making her worry. If she drinks with Venus and consequentially becomes sick, she refuses to let Jupiter find out and wants to keep the extent of her illness away from Jupiter.
It is proven that they have a romantic connection, however Neptune refuses to admit it in fear of what people may think, they kiss in the 7 minutes in heaven segment; you get an achievement for this.
Much like Jupiter, Neptune thinks Venus is trying too hard to be "good" and wants to persuade her to be "bad." In order to accomplish this, she frequently threatens and intimidates Venus to cause her to be more mean and lash out at people, but Venus generally refuses. She feels that Venus's kindness is due to her wanting something, and that her kindness is therefore dishonest.
- In the opening scene, Neptune is texting/using a messaging app to talk to someone who she has saved in her phone as Idiot<3Jerkface
- Her username on the messaging app is RestingWitchFace
- Neptune wears star earrings which look similar to sailor moon's star/moon earrings, which is likely done on purpose, as Sailor Moon is mentioned in the description of the game: "WE KNOW THE DEVIL is a story about everyone who made you cry at summer camp. It’s about missing your Sailor Moon VHS tapes."
- Neptune has an odd sleep schedule, being excellent at waking up and falling asleep, but only on her own schedule.
- She plays the card game Euchre
- Neptune got housed into Slytherin by a Harry Potter quiz.