Serendine is a petite yet voluptuous young woman with a confident expression. She has pink eyes and light pink hair in a complex style: straight bangs, a purple headband, and several long braids, ending in metal rings. There are also two loops of hair framing her face. She usually wears a military uniform: a transparent tunic, a low-cut breast plate with a spider design, shoulder plates with a floral design, a purple cape, a metal thong, shin guards and boots that reach her thighs. She carries a sword at her waist.
Serendine seems to have an energetic personality, and speaks with confidence. She's aware of her reputation as a tomboyish princess, but she doesn't seem to care; she's also proud of the fear she awakens on Parthevia's enemies. She has a familiar treatment with the people she's close to, and cares about Drakon as if he were of her family.
Serendine can become brutally angry if someone speaks ill of her father the Emperor, injuring the person in question by herself and also threatening with torture, though it's unknown if she carries out her threats.
She is a prideful person and prefers to be treated more as a warrior than as a girl. Since they were children, Serendine and Drakon were very close, and Drakon used to follow her around.
Dragul is thinking about the mission that is entrusted to him, and thinks aloud, saying that his brothers would never be assigned a mission of this kind. Serendine appears behind him and says that he shouldn't speak of such things so lightly inside the palace. She then greets him, saying that it's been awhile. When Dragul formally greets her, she says to call her just Seren, since it's shorter, and she addresses to him as Dragul Jr. Dragul asks her to call himself only Dragul since Jr was his childhood name. Serendine answers that he's too serious at times like these, and reminds him that when he was little he was a sweet little brother who followed her around like a duckling. Then she leaves that topic and says that she's heard that Dragul has been appointed the commander in the conquest corps. Dragul agrees, and says that, even if he's only the youngest son she treated him like one of her own family, and swears that he won't fail into the quest, because she will never do anything to soil her reputation. Serendine hits him on the head and says that she already has a terrible reputation as the Venomous Spider Princess of Parthevia, but that she likes this nickname, and thinks that suits her. Then, with a serious face, she says that if Dragul dies she won't forgive him, and takes her leave.
Serendine appears in Dragul's flashback when he's fighting against Sinbad inside the Dungeon. Serendine and Dragul's eldest brother, the Left General of Parthevia, Barbarossa, have been engaged and Dragul is formally congratulating them. Serendine is sitting next to Barbarossa, with a sad expression, and when she hears Dragul expressing his joy she becomes sadder, about to cry. She begins to say something but Barbarossa interrupts her, who thanks Dragul in an emotionless way and says to to the princess that he promises her a prosperous future of Parthevia. Dragul remains silent and Serendine's eyes fill up with tears.
After Sinbad and Drakon return from the Dungeon, she is seen staying with the army in the Contastia Harbor where Sinbad is said to be seen frequently. She orders her soldiers to capture Sinbad if they see him, and when her assistants tell her that there's no need for her presence, she answers that now they don't have many soldiers to mobilize, and she thinks that will make Sinbad pay for hurting Dragul. Then, some citizen begins to complain and insult the Emperor, which makes Serendine become furious and attacks the person who offended her father. She's about to punch the man again, when Sinbad suddenly appears and stops her. Sinbad calls Serendine "Cute girl", much to her assistants' dismay, who quickly introduce Serendine as the first princess of Parthevia. Serendine confronts Sinbad and poisons him, but he manages to steal the antidotes from her and embarrasses Serendine by totally exposing her chest. Sinbad takes her as his hostage and boards his ship, but soon releases her when he begins his journey, calling her "cute girl" again.