Penny, known as Patie (パティ, Pati) in the Japanese version, and Uri, known as Ururu (ウルル) in the Japanese version, are supporting characters and major team that début during the Ancient Mamodo Arc. Penny starts off as a enemy but ultimately redeems herself and becomes a valuable ally to Zatch and co.
Not much is known about Penny's past except that she fell in love with Zatch at first sight after he entered her private island. Since then, Penny has constantly been pursuing him and keeping him her first priority. After meeting her partner Uri, she sets out on a quest
Penny is a girl who likes pretty things and has a preoccupation with her beauty. Initially, she seems fairly harmless, if haughty about her appearance. However, she has obsessive feelings of love for Zatch Bell, and becomes violently angry when rejected by him. During her second match against Zatch, she interprets his desire to reconcile with her and be friends as a desire to marry her, showing that in her obsessiveness she can jump to rather drastic conclusions.
Initially, Penny has no compunctions against immoral actions like committing robbery or assault, and willingly joins Zofise's army of ancient mamodo as one of its heads alongside Byonko after learning that Zatch has amnesia and does not feel romantically inclined towards her, but gains a fearless, brave and self-sacrificial demeanor when she risked her life to take on Demolt and protect Zatch, to make up for her selfishness and sins despite knowing she can't defeat Demolt.
Penny wears a light and dark blue dress with a pink heart-shaped chestplate. She wears pink ballet shoes, and has a white ball attached to her dress in the back, mimicking a rabbit's tail. Her hair is styled in two pigtails pointed upwards, each wrapped in pink bows, and she wears a tiara. In the illustrations on the covers of the manga, her hair is a silvery blue color, but in the anime, it is turquoise. She is several inches taller than Zatch, not counting her pigtails.
During her battle with Demolt, she cuts her hair to shoulder length, but at the end of the manga it is restored to its original length and style.
Penny first appears looking for Zatch, proclaiming to be his girlfriend. Zatch later discovers she actually fell for him in the Mamodo World. When she saw him fishing on her private beach, she used all possible means to try to interact with him. Upon arriving at the Human World, Penny made a partnership with Uri, a poor man trying to get food for his family: Penny would help Uri feed his family, and in return he'll accompany her to help find Zatch. When she finally tracks Zatch down to Japan, Penny discovers the hard way about Zatch's lost memories, going absolutely berserk and forcing herself to fight him either to make him remember their (one-sided) love or to eliminate him from the tournament. Zatch proved his strength against Penny, but she is ultimately saved by the actions of Byonko moments before getting blasted by Zatch's Bao Zakeruga and allowing Uri to escape with both of them. Her love for Zatch is so great that she wears panties with his face stamped on them.
After escaping, Penny meets with Byonko's boss, the evil Milordo-Z, who offers her the chance to help him control the Ancient Mamodo and win the tournament. Seeing this as means to get revenge on Zatch, Penny takes the offer and leads a squadron of Ancient Mamodo into battle. Over time, she discovers her new servants lack the free will or abilities to fight for themselves and doubts the decisions she made.
Penny returns with Byonko to stop Zatch and company from reaching Demolt, but decide to move aside after everyone tells them their wrongdoings, as well as seeing Laila struggle with leaving the Moonlight. When Zatch and his allies appear hopeless fighting Demolt of the Four Supreme Mamodo, she and Byonko finally turn against their master, with Penny destroying the sustaining Moon Stone assisting the enemy with her So Giaku while her book is burned. Her final wish while being sent back is for Zatch and the others to forgive and play with Byonko when they return to the Mamodo world, which they agree to. Zatch also forgives Penny for her actions.
Penny is seen when Zatch is remembering those who are important to him during the battle between the final 10 Mamodo. During the final battle between Zatch and Clear Note, through the power of the golden spellbook, Penny's spirit helped out Zatch and Kiyo to defeat Clear Note when Kiyo casted Shin So Giaku along with Byonko's Shin Nyushirudo. Penny is last scene at school with Byonko, where she is "coincidentally" put in the same class as Zatch, whom she still retains feelings for. After the Ancient Mamodo Arc, Uri found employment as a chef in some restaurant, and is only seen again when Zatch prepares to battle Clear (which he is oblivious to), baking a cake in the shape of Penny's hairstyle.