David

David is Serenity's companion who guides her through the inner halls of Salem State Hospital & Asylum who's soul is trapped in a teddy bear. He is the lab assistant/partner of Dr. Aleister in the decoding of the Demons' Score.

During his research of the Demons' Score, David had his soul pull out of his body. When Serenity arrives at the Hospital, he is surprised to find he has become a teddy bear. Realizing that Serenity has the completed Demons' Score, David helps her on her journey to find her father.

David reveals to Serenity that he was Dr. Aleister's lab assistant/partner, much to Serenity's surprise. He was the one who introduced the doctor to a book filled with musical scores composed by a demon. They worked together to decode the tome into the Demons' Score, which resulted in a portal to Hell opening, and also put David's soul inside the teddy bear.

When the duo encounters Astaroth, the demon refers to David as "the snake." David claims to not know her, to which she responds by attacking. Serenity unlocks a new power and defeats Astaroth, claiming her soul in the Demons' Score.

During the final fight with Satan, Serenity hesitates and leaves herself open to the demon's blast. At the last moment, David jumps in front of the blast and his body is destroyed. His selfless act triggers Serenity's final form which allows her to defeat Satan.

With the Demons' Score completely upgraded, Aleister emerges from Serenity's phone. David returns and tells her that Aleister was to become a god and she is the doctor's experiment, meant to be his messiah. David gives her a choice to either follow her father's plan or make her own destiny. Serenity raises her sword and strikes down Aleister and choose to set her own course.

David is revealed to be Lucifer, who fell from Heaven to wedge war with God.