Venus was one of five turtles exposed to mutagen in the sewers. When Splinter gathered up all the turtles, he mistakenly left Venus behind. Somehow making her way to Chinatown, she was discovered by a shinobi magician called Chung I. Chung I took the turtle with him to China where he raised her as a daughter and named her Mei Pieh Chi. He also trained the turtle in the art of Shinobi. Apparently, Chung I would, on occasion, travel to the realm of dreams and encounter Splinter. Each swapped stories of their turtles, choosing to keep them a secret until the time was right. In his possession, Chung I also had a glass mirror, within which were trapped humanoid Dragons. It was Chung I's purpose to make sure the Dragons would never escape the mirror. The Dragons eventually crossed over into the realm of dreams, attacking Chung I and kidnapping Splinter's spirit. On his deathbed, Chung I revealed to the female turtle her true origin and told her her place was in New York. The female turtle traveled to New York, where she encountered the Teenage Mutant Ninja Turtles watching over the spiritless body of their master. After helping the turtles put an end to Shredder and the Foot Clan, she led them on a dream walk to rescue their master's spirit. Unbeknownst to her, the Dragons used this opportunity to enter the physical world. To celebrate their seeming victory, the five turtles and Splinter went for a picnic in the park but, were attacked by the Dragons. In the struggle, a statue of a woman was damaged when its arms broke off. Upon winning the battle, Mei Pieh Chi took the statue with her to the lair. This earned her the nickname of Venus de Milo after the famous statue, mimicking the other Turtles' artist namesakes. Venus seemed to have lived a sheltered life in China. Over the course of the series, Venus was portrayed as blissfully ignorant of some parts of western life and culture and, at times, equally naïve towards life in general. While proficient in fighting techniques, Venus was not trained in Ninjutsu like her brothers and thus, she would often use mystical orbs in battle. It was established early on in the series that, while the four turtles were raised as brothers, none of them were biologically related. This was done by the writers so as not to eliminate the possibility of a romantic relationship between Venus and one of the four male turtles, with hints leading primarily to Raphael and Leonardo. She and the other turtles teamed up with the Power Rangers in Space in the 1998 episode, 'Shell Shocked'.
Further appearances
After the cancellation of the show, an informal "second season" was formed on the official website, consisting of letters "written by" each of the turtles. An online dated October 1997 and called "Venus' Venerations" was added to the website, chronicling Venus' adventures alongside the turtles. After co-creator, Kevin Eastman, sold his share of the property to Peter Laird, "Venus' Venerations" was discontinued and Venus' letters were removed from the site. The rest of the Turtles' letters, however, remained and no explanation was given for Venus' sudden disappearance.
Comics
In the Image Comics series, writer Gary Carlson received only a few rules on what not to do, one of which being: "No female turtles." Venus was, however, parodied in the twelfth issue of the third volume, when an alien named Lurch transformed into a female turtle looking very similar to Venus. Some issues were even advertised with the slogan: "No girl turtle guaranteed." In the Archie Comics Venus was actually preceded as a female Turtle by April, who was briefly mutated into a Turtle with a white mask in one issue. Venus was succeeded with a new female turtle in the IDW Comics, where Jennika, a member of the Foot Clan and a good friend of the Turtles and Splinter, mutates into a female turtle from the mutagen in Leonardo's blood, via a blood transfusion to save her life after nearly being killed by Karai.
In other media
During an interview, Kevin Munroe, director of the TMNTanimated film, elaborated on Peter Laird's instructions saying that, "There’s absolutely no mention of Venus de Milo, the female Turtle. You can’t even joke about that with Peter. It’s just one of those things that he hates with a passion."
In the 50th episode of Robot Chicken, titled, "Moesha Poppins", Venus makes a very short cameo in a "Where Are They Now" skit, revealing that, after being kicked off the team, she tried to flush herself down the toilet and drowned.
In an episode of 2012's TMNT animated TV series, Raphael paints a female turtle-human hybrid, on the side of the Turtles' new Party Wagon, which Donatello admires it approvingly. The painting was named "Venus".