Sylvia Marbas

"No one is allowed to boss me around, except for Onee-sama. If you try to do it again, Sylvia will kill ya~! Is that clear?"

- Sylvia to one of her teammates Sylvia Marbas is an antagonist in the FanFiction High School DxD: True Maou written by demonicjester01. She's a Half-Devil assassin brought up in the same institution where Lucina was trained, in which she was the second-ranked with Lucina herself being the first. She's also the current leader of the unit "Five Nights" formerly led by Lucina and one of Rizevim Livan Lucifer's personal soldiers.

Appearance
Sylvia is a beautiful sixteen-year-old girl with milky white skin, green eyes and smooth, orangish blonde hair reaching the middle of her back. For her short height, she is noted to have a very curvy physique with slender limbs that belie her extraordinary strength. Like all Devils, she possesses black, bat-like wings.

She generally wears the uniform of the Old Maou Faction's special assassins, along with white gloves. In the few casual occasions she happens to partake in, Sylvia has a preference towards dresses with longish skirts and different types of sweaters.

Personality
Sylvia normally behaves with a child-like and willful personality, doing whatever she pleases regardless of consequences or the thoughts of others. Raised from birth in the Old Maou Faction's institution to be an assassin and taught nothing more than that during her whole life, she has developed a twisted sense of value towards life in general, seeing killing those who defy her will or go against her as an aspect of life as natural as eating, drinking water or breathing.

However, she is not heartless by any means, as despite her words, Sylvia has a deep affection and care for her teammates and harbors an obsessive love for Lucina, calling her "Onee-sama" because she approached the lonely Sylvia in the past and told her she'll be her older sister upon being rejected as a friend. This very fact, in turn, causes her to initially hate Aslatiel and Wilhelmina. She adores Lucina with blind devotion and has expressed a great disdain for being ordered by others, with Lucina being the sole exception.

Sylvia also possesses a more vulnerable side rooted in that her parents sold her to the Old Maou Faction as soon as she was born and was then raised only as a tool, which has caused to have severe issues of self-worth. Feeling that her abilities for assassination are all she has to prove herself, Sylvia keeps doing the most work she can as best as she can despite not enjoying killing in the least. Her feelings of self-worth have been further damaged by the fact that she can't touch anything without exposing it to her Sacred Gear's poison.

Very unlike Lucina, Sylvia can cook surprisingly well, but shares her "older sister's" love for beer and bad aptitude with machines. She also is surprisingly shy, losing any trace of her murderous side and turning extremely meek after Aslatiel gets a glance under her skirt by accident.

History
Sylvia was raised since birth in a special institution of the Old Maou Faction that took in Devil and Half-Devil children and trained them into powerful assassins. Her talent and aptitude were very apparent and she quickly became top-ranked among the trainees at the time, that is, until Lucina dethroned her and became the new number one.

Shortly afterward, trainees who had restrained their jealously during Sylvia's time as the number one and Rizevim's favorite finally took this chance to attack her. In such a large group, they managed to overwhelm her and almost killed her, but Lucina witnessed this and aggressively drove the jealous trainees away.

Seeing how alone Sylvia had always been, Lucina offered to be her friend. Sylvia rejected such a thing, but Lucina then arbitrarily decided to become her older sister instead, at which Sylvia gave up and complied. Eventually, Sylvia began to call Lucina "Onee-sama" naturally.

Together with the fifth-ranked, seventh-ranked and twentieth-ranked trainees, they completed many missions and the bond between the five grew unbreakable. Sylvia was by far the most affected when Lucina ran away from the institution after becoming Aslatiel Bael's Queen.

Plot
TBA

Powers & Abilities
Immense Combat Skills: Being second only to Lucina in the Old Maou's Faction institution and having been enhanced even further since then, Sylvia is a remarkably powerful battler. She is normally able to prevail over vastly superior enemies through assassination rather than direct combat, but this doesn't stop her from fighting head-on with Lucina using the Rosa Atra and being slightly superior (albeit Lucina wasn't using her own assassin skills). She freely uses two martial arts styles developed for assassination: Flashing Sheath, the ability to attack extraordinarily fast without stances or initial movements, and Flashing Step, the ability to move incredibly quick in one burst, making an effect similar to teleportation that cause the opponent to lose sight of her for a moment. She's adept at fighting with both close-range weapons such as daggers and knives as well as firearms and her bare hands.

Demonic Power: Sylvia possesses all the powers and abilites common to Devils, including the power to cast spells. Superhuman Strength: Sylvia possesses extraordinary amounts of physical strength, enough to push back a monster of over one metric ton in weight with a single kick and briefly clash with Aslatiel in close-quarters combat.
 * Disease Manipulation: The Marbas Clan's trait, Sylvia has the ability to manipulate illnesses and infectious agents. As long as she possesses the necessary knowledge, she can heal and cause virtually any disease, as well as control their severity or stages.

Immense Speed: Sylvia's extraordinary speed is one of her deadliest weapons when combined with her unpredictability. In immediate bursts, she appears to teleport and can kill the confused opponent with a single, frontal blow to the neck before they can fully process what happened. She has no problem with moving just as fast even in rough terrain.

Flight: Being a Half-Devil, Sylvia can use her wings to fly.

Equipment
Viral Cornucopia: Sylvia's Sacred Gear, which has the ability to create various kinds of poison according to the wielder's imagination and knowledge. The poison is released from the user's hands and can be used through direct touch, by smearing it on weapons, dipping it in food, etc. While immune to her own poison, this Sacred Gear is considered a curse as it can't ever be deactivated, leaving Sylvia unable to touch anyone or anything without subjecting it to the poison that is naturally produced regardless of her thoughts or desires. Needles: Sylvia's weapon of choice are pointed metal sticks similar in size and shape to a drumstick that she carries in large quantities. They can be used in close-range combat to kill even powerful beings with a single strike to the head, neck or other vital spots. Since they work for making holes rather than cutting, their use is similar to an awl's. They can also be smeared with her Sacred Gear's poison for increased lethality and thrown with great accuracy at even a target who is more than twenty meters away from Sylvia.
 * Balance Breaker: Unknown Status.

Trivia

 * Sylvia's body measurements are B83-W56-H84, her height is 154 cm and she weighs 47 kg.
 * Her birthday is on August 22nd.
 * Her blood type is B.
 * Sylvia's appearance is based off of Prinz Eugen from Kantai Collection (Kancolle).
 * Her favorite food is home-made fried chicken, while her least favorite is pudding.
 * Sylvia's ideal man is someone who would treat Lucina well.
 * In demonicjester01's headcanon, Sylvia would be voiced by Ari Ozawa in Japanese, known for voicing Prinz Eugen from Kantai Collection (Kancolle) and Kirin Toudou from Gakusen Toshi Asterisk.