Allen Avadonia (Alexiel Lucifen D'lautriche)

in love with you, loyal to his sister, not very tall

Conceptualization and Origin
Their original surnames, Lucifen and d'Autriche, are a reference to Lucifer, the patron demon of Pride, and Marie Antoinette, respectively.
His adopted surname, Avadonia, appears to be a corruption of Abaddon, which means "destruction" in Hebrew.
Allen's name is partially inspired by the name of his Vocaloid representative, Kagamine Len, with "len" at the end of the name; similarly, his birth name, Alexiel, shares the "le" with Len.
Allen has a parallel with Jesus Christ; both were punished for crimes they did not commit, were executed at three in the afternoon,[7] and appeared to their allies many times after their death.[10]
Interesting facts
Allen was executed the day before his fifteenth birthday.[7]
Allen shares the same birthday (December 27) with his Vocaloid.[11]
The Celestial Garden Master's pose in Evils Court is reminiscent of Allen's pose from the Evil Daughter PV; similarly, both are portrayed in such a position prior to their formal debut.

Personality and Traits
"Riliane... You're a bad girl. But... If you're called bad, then that same blood runs through my veins. If you're "The Daughter of Evil," then I'm "The Servant of Evil." Because I will take your place, in my place you... will live."
—Allen[source]
Allen was a responsible, loyal, and troubled young man. As a child, young Alexiel was gentle and trusting, submissive to his sister, and afraid of becoming selfish, as he later did. Although less so after his adoption, Allen continued to show kindness to others, particularly to his friends and his new family. As a servant, he also maintained a professional and courteous demeanor, especially when in the presence of his superiors.

In addition to this, Allen possessed a strong sense of justice and his own set of moral principles, which began in childhood and was exacerbated by his upbringing at the hands of Leonhart Avadonia. This led him to be disgusted by injustice and harm to the innocent; he typically took the initiative to help others, particularly those he cared about. During his service to Riliane, Allen found himself deeply conflicted as he strayed from his moral compass; because of this, he came to consider himself as "evil" as she was, even after her death. His desire to help was often hampered by his own indecisiveness about what the right course of action was.

As a result of his traumatic childhood, Allen was naturally unsociable and cynical, as well as prone to sarcastic remarks about his sometimes absurd situations. Allen was also sensitive to ridicule and arrogant about his abilities or opinions, which could make him argumentative or competitive. He was also extremely pessimistic about the world around him, adopting a view that everyone was his enemy when he was young, which, although toned down, he later transferred to his view of Riliane. At the end of the world,

"How can I say this? This may be a little too arrogant coming from a mere servant, but I want to protect the princess."
—Allen Avadonia[source]Allen Avadonia, born Alexiel Lucifen d'Autriche and known as the Servant of Evil, was the last prince of the Kingdom of Lucifenia and the most loyal servant of his twin sister, Princess Riliane. After their father's death, Alexiel and his twin sister were separated by a political dispute, and he was publicly declared dead. Adopted by Leonhart Avadonia, "Allen" returned to the royal palace to serve as his sister's servant, helping to eliminate any opposition to Riliane's tyranny.

Skills and Abilities
"Deep thinking? It's not bad to think about things. But nothing begins without action. You have a habit of trying to complete things too much in your mind."
—Sickle criticizing Allen's inability to act[source]
Allen possessed an analytical mind that helped him grasp politics from a young age, making him a capable diplomat despite his lack of involvement in political affairs. This also enabled him to be a skilled planner, including the ability to adapt his plans in case of complications,[1] though he sometimes fell short of expectations. Allen was traumatized and could sometimes cease to think rationally when faced with decapitations. Also, after his death, he gained extensive knowledge of Bolganio's history through the Black Box.[2] However, as he could only read the memories of souls who had gone to the Celestial Garden, there were gaps in his knowledge regarding demonic contractors.[3]

Having trained under Leonhart, Allen was a skilled swordsman and knew several techniques; he even developed his own technique, the Unicorn Style, where he centered his sword in front of him while attacking. However, due to his lack of combat experience, Allen was prone to talking too much in battle and lacked the quick thinking to adapt to more difficult opponents.[4] As a servant, the boy was adept at a variety of tasks such as cleaning,[5] cooking, and running errands,[6] though he considered his skills inferior to those of his fellow servant, Ney.[5] He was also skilled at horsemanship and could sing.[1]

Because of his resemblance to his sister, Allen could disguise himself as Riliane in appearance and voice, though only to those who had not personally met either of them.