Ruby Gremory - (alt. reality Mio Naruse)

Ruby is shown to be a calm and quiet person, especially around those she isn't close to, but she's rather talkative around her closest friends and family - especially Rias. It is noted that she can be rather quick to anger based on the situation, mostly if someone close to her is threatened, insulted or harmed - for example, in her younger years whenever Riser Phenex tried to move in on Rias. Whenever it happens, Ruby is always first standing between them, refusing to budge.

She has a general dislike for perverts, having always stepping in to protect her sister from Riser, and even in initial interraction with Issei Hyoudou. Ruby openly expresses her harsh cricitism towards Issei and his other "stooge" friends and gives Rias a bit of grief about why she chose him of all guys. But as time goes on, she witnessess Issei's determination and strength and over time mellows her tone towards him. Although she still doesn't hassitate to playfully chastise him on his lechy behavior. She herself doesn't fall for Issei, however she does learn to trust him with more personal topics.

Despite her occasionally short fuse towards whoever appears as problematic, Ruby is rather caring, honest, and compassionate. Although Ruby attempts to act brave and calm all the most, deep down she is quite insecure about her current situation - as the youngest Gremory sibling, she doesn't yet have the priviledge of leading her own devil team. Not to mention she didn't inherit the Destruction Magic.

Feeling insecure throughout her younger years, she always hesitated socializing with other young devils. Instead, she spend most of her time learning "basic offensive" elemental magic (Fire, Ice, Lightning) from the dragons living in the mountains near Gremory estate, even having chance encounters with the former Dragon King himself, Tannin.