She is voiced by Narumi Takihira in the Japanese version of the anime, and by Cherami Leigh in the English version of the anime.
Patty is 'physically' older than Kid, Black☆Star, Soul, and Maka. She has chin-length, bright yellow (blonde) hair with bangs, light blue eyes and she has bigger breasts than her sister even though her sister is older and taller (a difference in body structure that causes no end of frustration to their meister, Kid, as it makes them asymmetrical in human form).
In Soul Eater NOT! Patty is usually seen in her Deathbucks Café waitress uniform, consisting of a short skirt and a skull-shaped tiara. When not working at Deathbucks, she wears a sleeveless top and jeans. Like her sister at this time, Patty also wears a Shibusen monitoring bracelet, with a skull logo on it resembling Death's mask, to monitor her location while on probation for previous crimes committed in New York City, Brooklyn and elsewhere.
In their initial appearances in the manga, both Thompson sisters wear cowgirl outfits: a tight, red, sleeveless, turtleneck belly shirt with a white tie, cowboy hat and black, high-heel boots. However, unlike Liz, Patty wears puffy shorts. There is also a subtle difference in her hat. Liz's hat has rims that slant forwards, whereas Patty's hat has rims that are in a perfect curve. Later on in the anime, both sisters wear white jackets over their outfits. Upon their transition into Spartoi, Patty usually retains a hat while Liz does not.
Like Liz, Patty's soul has a pink color and has two curved triangles representing her hat. In Spartoi uniform, Patty wears a zip-up top over a blue vest and a jacket with a high collar like Liz. She keeps her puffy shorts but replaces her cowboy hat with a hat that has floppy 'ears' on each side.
When transformed into a boy upon entering the Book of Eibon, Patty is shown to have shorter hair covered by a beanie hat. She also resembles her psychotic self a bit more, as her eyes look slightly more crazed than in her female form. She wears a white jacket and shirt and dark pants like Liz. The only difference is that Patty has the Spartoi logo on her left shoulder and a large Shinigami skull emblazoned on her back.
Patty is mostly seen speaking in a sing-song voice, as she often says '♪' after her main speech. She acts and speaks like a young child. She pronounces words like "hello" and "sorry", as a child would "hullo" and "sowwy". She seems to still be learning about simple things such as assigning animal noises to the right animal. In fact, Patty is just learning to assign the right name to the right animal. She is certainly unaware of more complex concepts, such as those of genders other than simply male and female. However, these may not have been explained to her due to her generally childish demeanour and inability to understand a lot of things, as exemplified by Liz congratulating her on simply getting animal names right. This lack of knowledge may be due to her growing up on the streets and presumably not having an education.
She is very naïve and simple-minded and doesn't seem to take anything in a serious manner, often laughing when something bad happens. While taking an important written exam, instead of answering questions, she began making an origami giraffe out of her test papers, then "broke its neck". Her current personality differs from the seemingly aggressive personality she had during her time in Brooklyn, developing her current personality after she met Kid. Unlike her sister Liz, Patty enjoys the drama brought on by Kid's perfectionist attitude; though she does cheer him up when he gets down on himself about it.
On the few occasions when she loses her temper, her childlike personality is replaced by a somewhat psychotic-seeming anger, as if her personality reverted back into her past street life in Brooklyn. It can be so frightening that it managed to scare Kid into running through a minefield of asymmetrically placed Tadpole Bombs on the way to stop Asura's revival while crying. There have been times though, that Patty's childishly naïve personality disappears to make room for a more serious personality, suggesting that her bubbly personality may be a mask, or merely how she wants to act. These changes are more evident in the manga, a recent example of which was seen after Kid got 'collected' by Noah. Patty uncharacteristically called her sister a coward when she refused to fight Noah, and showed a surprising maturity by comforting her sister afterward. Whether these qualities count as her own form of madness has yet to be clarified.
When having her gender switched inside the Book of Eibon, Patty's personality leans towards his more crazed side, with a higher amount of aggression as he threatens to "beat (Index) up" with a sadistic look on his face.
- Her English Voice Actress, Cherami Leigh best known voicing as Biyomon, Yokomon, Maki Himekawa from Digimon Adventure tri., Asuna from Sword Art Online, Elizabeth Midford from Black Butler, Sarada Uchiha from Boruto: Naruto the Movie, Himawari Kunogi from xxxHolic and Natsumi Hinata from Sgt. Frog.