Percival looks like a very young boy showing a small and lean figure, despite being in his late adolescence, with green hair and purple eyes. His outfit composes of tunic cloth and short. He later wears his grandfather's purple horned iron helmet and an orange cloak with a brooch shaped like a serpentine creature biting his own tail.
After an encounter with his father Ironside, Percival harbors a very large cross-shaped scar on his upper body, tilted slightly to the right. The same scar also extends to his right arm, which will align perfectly with the scars on his body when standing with arms down.
Despite being a teenager, Percival is essentially a child in body and mind.
Because he has grown up in an isolated environment, away from the world and humanity, with his grandfather as the only acquaintance, he overflows with curiosity towards everything he does not know, and since there is much that he does not know, he is always excited.
Due to his lack of experiences in life, he is extremely naive, easily relying on people he barely knows, to hand over all his belongings, or to follow them where they want.
Having lost his grandfather, whom he loved more than anyone else, Percival leaves his home, in large part to find his murderer, but also because he wants to go on adventures just as his grandfather inspired him to do so.
Appreciating the words of his grandfather, Percival tries to act as a Holy Knight should, facing the evil and protecting the weak.
He seems to be quite interested in women, observing Elva's body (and pawing her breasts) when they were bathing in the lake, but instead as a genuine curiousity rather than lustful intent.
Percival was born 16 years ago, during the year of the New Holy War.
The details of his birth are still unknown, but at some point before or after this, his father betrayed Camelot, with his grandfather accompanying him, leaving the kingdom. After parting ways, his grandfather took Percival to God's Finger, where he raised him in total isolation until the beginning of the series, teaching him to fight since he was only three.
Percival is first seen chasing a Roc Bird while being assisted by his grandfather, Varghese, while the two live in isolation on top of God's Finger. After eating the creature, the two take part in a match of Gouren in which Percival loses and vents on his loss but his grandfather reassures him of his strength.
The old man suddenly remembers that tomorrow is Percival's sixteenth birthday and explains how turning 16 is the entrance to adulthood and how he will soon set off on his own personal journey. However, Percival expresses no interest and claims that being with his grandfather is enough, much to the latter's shock. Later that night, Percival sneaks outside and remembers his grandfather's words and reveals he does in fact wish to seek these thrills but after waking up the next morning, finds a strange knight in red armor approach the summit on a flying boat.
The boy is shocked and amazed at how one of his grandfather's tales are true while the knight asks if Varghese is around. After directing the knight in the direction of the house, Percival gets an ominous feeling and returns to the house to find the red knight attacking and mortally wounding Varghese. Percival attempts to attack but the knight easily overpowers him and attempts to silence the boy by using his power to give him a star-shaped cut through his body and further attacking Varghese, leaving the two to die in the snow.
Percival, despite his wounds, comes to his dying grandfather's side who explains that the red knight's name is Ironside and that he is his son, thus making him Percival's father. The boy is confused as first due to Varghese having told Percival that his father died when he was very young and his grandfather apologizes as he had to lie for reasons unknown. Before dying, he tells Percival that if he wants to understand why, he must seek out his father and ask him.
Some time later, Percival sits in front of Varghese's makeshift grave while the man's helmet and cape left to the side. He remembers his grandfather's last words and resolves to set out in search of his father to find out why he attacked them.
Despite his small size, Percival is incredibly strong, beyond that of almost any human adult. This is best shown when he takes out a monster wolf the size of a house with nothing more than a slap to the face.
Percival is also extremely resilient, standing upright showing little to no pain despite being hit with an extremely powerful attack from Ironside which would leave a massive scar on him.
He has also shown the apparent ability to aim at targets behind him, how he achieves this feat is not yet understood. But it seems that this happens even when he fires at a target right in front of him with his bow and arrow.
He seems to be extremely talented as a Holy Knight, managing to awaken his magic in the middle of a difficult fight, only to unconsciously use it to reverse his situation and manage to dominate his bases in a matter of minutes.
Percival has a great constitution against drugs and sleeping chemicals; waking up shortly after being given Belladonna leaves that were intended to knock him out for ten hours.
希望, Hōpu」: Percival's Power manifested during his fight against Pellegarde. He is able to tap into the hope of his allies, allowing him to generate a magical aura around his body, or part of it. This aura can be used in several different ways. Pellegarde speculates, due to its multiple uses, that it could be a "Hero Type" magic that only appears in one in ten thousand people.
- Enhanced Durability: Covering his body, Percival significantly reduces the damage taken from magical (and probably physical) attacks.
- Enhanced Healing: Covering his body, Percival can heal injuries such as severe burns in a matter of seconds.
- Enhanced Strength: Covering his fists, Percival's physical strength increases considerably.
- Form Taking: The aura can take form of anything Percival imagine. Like a hand to hit his enemy, or a mouth capable of absorbing magic attacks and throwing them back.
- Magic Golem Creation: Takes the form of minimized clones of Percival. It is unknown how much control he has over these clones (since he created them unconsciously), but they seem capable of simple acts such as swarming Percival's enemy and they are even able to speak single words. They seem to have considerable physical strength. The golems are also able to heal injuries.
- Flight: Covering his body, Percial can form wings and levitate in the air through his aura.
Varghese is Percival's grandfather and was his only family. Percival greatly admired and loved him, as the two had a very good relationship and never showed any signs of anger or annoyance with him. Percival was determined to give up his dream of adventuring in Britannia to accompany his grandfather so that he would not feel alone. In short, Varghese was the special person Percival wanted to protect above all else, and even if he doesn't show it, her death affected him a lot, crying during the cold nights when remembering the warm embrace of his grandfather.
Ironside is Percival's father, as well as the murderer of his grandfather Varghese. Although at first he was very curious about its origin and particular means of transport, Percival is very resentful with him, although it is not clear if he hates him to the point of wanting to kill him, he is determined to find him and defeat him to find out why he did what he did.
- Percival's brooch (the snake swallowing it's own tail) is the mythical creature called "Ouroboros". The ouroboros is often interpreted as a symbol for eternal cyclic renewal or a cycle of life, death, and rebirth.
- Percival is named after his namesake Percival, one of the Knights of the Round Table in Arthurian Mythology.
- Percival is right-handed.
- Percival's helmet weighs 7 kg.