Ravel is the youngest child among the four Phenex siblings and the only daughter of the Phenex Family. She became Riser's Bishop at some point prior to the start of the series.
Ravel is first shown to be spoiled, arrogant and snobbish during her debut, but is later revealed to be a well-mannered, modest, elegant, and polite young girl, but shown to be initially harsh towards those whom she dislikes. She's very loyal to her older brother, as she is seen diligently obeying his authority. She strongly believes that her brother is so powerful, no one could ever possibly defeat him. However, after witnessing his crushing defeat at the hands of Issei Hyoudou, she becomes attracted to him and later falls in love with him as the series progresses, albeit in tsundere tendencies.
In truth, she does not really mind being one of Issei's "servants", or otherwise his "concubines", just as long as she can continue to be by his side, desiring to be traded as one of Issei's Bishops when he gains peerage, for she only wishes to be of use to him. Later on, she seems to have grown very proud of being Issei's manager and therefore continues to study diligently, so as to serve as his support in the future.
Despite her young age, she's very intelligent, mature and perceptive, being able to understand the atmosphere of any situation as well as surmise Issei's thoughts just by simply looking at him. She is also shown to be a gifted strategist, serving as Issei's main strategist and second in command of his peerage. In this position, Ravel appears to be quite strict as she has her own expectations and standards when it comes to the suitability of someone to serve under Issei, such as when she denied Kuroka's offer to make Le Fay Pendragon Issei's contracted magician due to the latter's affiliation with the Khaos Brigade or when she was initially against letting Elmenhilde Karnstein join Issei's team.
Ravel has also shown a ruthless side, being relentless in securing victory for her team. This is seen when she consistently read out the manga about Issei and Kiba to Tsubaki Shinra, despite the latter's obvious discomfort and pleas to stop. However, Ravel is also shown to be quite fragile hearted as seen when she cried when she believed she failed Issei after their defeat against Dulio's team in the Azazel Cup.
Despite her maturity, Ravel is also stubborn and childish at times, having a habit of wanting other people's belongings, as stated by Riser, this is seen when she fights with Koneko over Issei's lap or when she fights with the other girls over Issei, despite being the one who manages everything.
Riser is one of Ravel's three older brothers, being the youngest of the three. Originally, Ravel was part of Riser's peerage before she was traded to her mother's peerage for an unused Bishop piece, though it seemed that she herself did not take part much in Riser's Rating Games. The reason Riser added Ravel to his peerage (likewise his harem) was because he had wanted an imouto (little sister) type girl, as well as a tsundere type girl. He also seems to enjoy teasing her about Issei, referring to him as Ravel's future husband, much to Ravel's embarrassment.
Ravel did not think much of Issei when they first met, but she started to admire him after he defeated her brother Riser to get Rias back. She was shown to have developed feelings for him by Volume 5, and have fallen in love with him by Volume 12, cemented by her feelings of grief and sadness over his 'death', and her happiness at his return. It is implied in Volume 9 that she enrolls in Kuoh Academy so she can get closer to Issei, and moves in with him in the following volume. She happily accepts Sirzechs's request of becoming Issei's manager and continually works hard for him, such as finding a suitable magician for him to make a pact with. She also constantly fights with Koneko over who gets to sit on Issei's lap. Ravel explains at the end of Volume 14 that the reason why she grew to admire and later fall in love with Issei was because of stories her servant used to tell her as a child. These stories were about heroes who sacrificed or suffered greatly in order to protect people and the ones they love. As she grew, she gradually forgot these stories but recalled them after seeing Issei getting hurt, beaten, and eventually winning in order to save Rias. She then began to research more about him, learning that despite his perverseness, he cares about his friends and family and how much he resembled the heroes that her servant used to tell her as bedtime stories. It then grew to the point where she wanted to get closer to him, to her fully realized hero and idol, and support him as the person she respects and developed feelings for.
In Volume 22 upon Issei's promotion to High-Class, Ravel's mother approaches Issei to remind him of the promise they made about allowing Ravel to join his peerage. Ravel is then traded to Issei, becoming his second official Bishop.
In Volume 23, Ravel became bolder after becoming a member of Issei's peerage, such as shyly expressing her desire to sleep with him while Rias and Akeno aren't around and wearing a transparent white negligee and having him grope her. She has even stated a desire to be the object of Issei's perverted desires, stating that her mind and body belonged to him, her King, this caused Issei to have a lewd fantasy about her letting him grope her breasts. She's more determined as she allows him to touch and squeeze her breast and fights with Church Trio for his affections and who gets to sleep with him. Ravel appears to be Issei's second in command, as well as his mentor in his peerage due to her experience as a High-Class devil. Ravel's mother has even encouraged Issei to fully utilize Ravel's potential. Despite Ravel's strict nature as his manager and peerage member, Issei has shown complete trust in Ravel's judgement, due to her experience. Ravel is deeply saddened by her team's loss to Dulio and his team and Angels, feeling she let Issei down and cried deeply, but was hugged and comforted by Issei, who assured that they would become stronger and took Ravel away from everyone else to console her and hear her emotions. Milicara has even noted that Issei deeply treasures Ravel, showing how close the two of them have become.
In Volume 24 after fighting off the Grim Reapers, Ravel unhesitatingly allowed Issei to use her breasts to contact Koneko and Kuroka. As Issei squeezed her breasts Ravel moaned blissfully, showing pleasure in being the object of Issei's perverted technique.
In Volume 25, Ravel was present when Issei's future brides fought over him and despite trying to manage the situation, Ravel eventually joined the fight herself.
Ravel and Koneko have a hot and cold relationship due to the fact that she is a Phoenix and Koneko is a Nekomata, alluding to the natural rivalry between birds and cats. They see each other as rivals because both are in love with Issei and will openly compete with each other for his affections. However, they have been shown to get along and have become friendlier to each other as time goes on, usually only showing hostility to one another when it involves Issei, such as in Volume 14, where they are shown to be fighting over the spot on Issei's lap. Koneko is also hinted to feel inferior towards Ravel due her larger breasts, feeling Issei prefers Ravel to her.
LOTM: Mageddon Trilogy