She is a cute silver-haired girl. Her heterochromatic eyes glisten in deep crimson and light sky blue. This, among her many strikingly beautiful features, is the most prominent one. What garners the most attention, are two pure white teeth that peak from within her small lips. When her small lips part, they reveal a set of pure white fangs. She is commonly seen wearing gothic dresses but seems to have a penchant for maid uniforms too.
She is considered by Rimuru as a 100% Tsundere. She gets along well with Adalman and contributes significantly to his research, it's stated she has even helped with Tempest's larger-scale experiments. She is very proud and extremely confident in her own personal power and army, as shown by how she found Clayman an amusing sideshow and fully welcomed The Eastern Empire's attack, in fact, if anything she was annoyed when Tempest ended up crushing said Empire. She bears a grudge against Veldora for destroying her last kingdom and is extremely thankful to Chloe for stopping him. Her feelings for Chloe, in fact, were enough to awaken Ultimate Skill Lustful King Asmodeus when Yuuki kidnapped her. Furthermore, she considers Hinata highly because of Chloe and is if anything envious of Rimuru for the same. She considers humans untrustworthy and advised Rimuru as such, but did not press the matter when he noted his intention to keep trusting them. Fittingly for a Vampire Matriarch, she seems to have a penchant for finer things.
300 years ago, Veldora trashed a human city and attacked Demon Lord Ruminas, and subsequently destroyed the Vampire Kingdom. He was then defeated by the dispatched Summoned Hero. The beautiful hero imprisoned him in her Endless Prison, sentencing him to live his days in monotonous boredom. She then proceeds to found a new kingdom which in time become Holy Kingdom Ruberion, with her being considered a god.
Rimuru Tempest: She envies Rimuru due to Chloe's feelings for him, that said she doesn't seem to hold this against him and at least once offers him what for her is sound advice. They are firmly allied in rescuing Chloe.
Adalman: as a former member of her faith Ruminas gets along well with Adalman and helps him develop several of his Holy-Demonic spells. Her seven sages apparently caused his death without her knowledge or consent, indeed it's a wonder if she was even aware he had died. Now that he's returned, the sages worry he'll be a threat to her, as was apparently the reason they wanted him gone to begin with.
Chloe O’Bell: Ruminas considers her a friend (and maybe more), but is borderline obsessed with her for saving her from Veldora.
Hinata Sakaguchi: Ruminas very much believes that Chloe's friends are her friends and almost immediately helps save Hinata's life.
Veldora Tempest: Because her old country was destroyed by him, she holds a grudge. For his part, Veldora seems to want to apologize after watching Tempest's rise, since he can now appreciate the weight of his actions. Although at the present era it's unknown whether she actually still hates him, she was even ready to thank him when he showed up to save her during the Tenma War, however he ruined that by admitting he waited to make a dramatic entrance and then, accidentally, destroyed her newest county while trying to save it, even then she swallowed her anger, thinking it was necessary, until Veldora used a skill to make her lands fertile and strong, which succeeded at the expense of literally every man-made structure. Needless to say, Veldora's involvement in anything almost always seems to incur her wrath, usually deserved.
She is noted by Rimuru late in the series to have True Demon Lord class strength. She commands several Vampire Nobles and human sages, who are comparable to unawakened Demon Lords at the worst of times. She has survived angel attacks numerous times as well, with enough leeway to shock later generation Demon Lords.
- Lustful King Asmodeus: She is able to bring the dead back to life on certain conditions. This Ultimate Skill governs life and death.