Renet Tilley is a rather reluctant, spoiled, and impulsive teenager whose parents, also denizens of the 79th Level, hoped that apprenticing her to Lord Simultaneous would help her develop some kind of common sense. Curious and impatient as she was, she did not care very much for studying. Renet first met the Turtles fooling around, when one day out of boredom she snatched her master's Time Scepter and was caught by him. She replied immediately and time-traveled off with Lord Simultaneous’ Sceptre of the Sands of Time to Earth - more specifically to 1986 New York City. Renet and the Turtles became friends, but Simultaneous appeared and sent Renet into a panic. Fleeing Simultaneous further, she and the Turtles went to 1406 A.D., straight into a castle siege. The castle belonged to the dark mage Savanti Romero, a former, but exiled student of Simultaneous, and the besiegers were the soldiers of Cerebus, who was after some scrolls, that Romero had stolen. Romero also managed to grab the Time Scepter, and the Turtles and Renet had to contend with Cerebus' help to attack the castle and get the Sceptre back from Savanti Romero. The force was no match for Romero's magic. Before it came to the worst, Simultaneous appeared. Romero attacked Lord Simultaneous who took the Time Scepter again and cast Savanti into prehistoric times. He handed the scrolls to Cerebus, sent the Turtles back again to their time, and sent Renet to wipe dust in his huge library to. Later, she assists the Turtles in defeating Savanti Romero in prehistory when Romero plans to alter the Earths orbit and prevent the asteroid impact that wiped out the dinosaurs, meaning humanity, and mutant Turtles, will never exist. After defeating Romero, the group is stranded in prehistory for several months after the Scepter is lost in the ocean, but it is eventually recovered. Renet makes a third appearance saving the Turtles from Romero's demonic bride, Juliet Romero. This time she appears as a deity-like woman with full control over her time manipulating powers.
In the 2003 cartoon, Renet (voiced by Liza Jacqueline) undergone some minor changes in her backstory, where she is shown to be quite a scatterbrained person who came to her friends with good intentions, but with little practical skill she caused some problems across space and time. This leads to her transporting herself and the Turtles back to the medieval age to which Savanti Romero was banished, which resulted in the loss of the Time Scepter to Ultimate Drako, the fused form of the Ultimate Ninja and Drako. It would later be recovered and entrusted to Renet again, leading to another encounter with Romero in the Cretaceous Period. She would later appear at April and Casey's wedding, watching from a distance.
In the IDW comics, Renet has her debut in a special story, where she "invites" the Turtles to the interdimensional Battle Nexus tournament. In this version she is also Lord Simultaneous' pupil in magic, dimension travel, and apparently his successor in the Dimensional Council. At the time in which she appears for the first time, the cruel Councilor Nieli hosted a series of merciless gladiator fights, which only he really liked. Renet was also against the games for personal motives, because one of the champions, the warrior Baltizar, had won her heart. For this reason, they brought the Turtles to the hub of the dimensions and helped the culmination of these events to instigate an uprising against Nieli which meant that Nieli was banished and the games were transformed into a far more peaceful affair.
In the 3D CG the 2012 cartoon, Renet (voiced by Ashley Johnson) is a young immature timestress from the future who, like Michelangelo, makes rash decisions that sometimes gets her and others into trouble. She is also becomes the object of Michelangelo's affections. After taking her master's time scepter to keep it out of the hands of mutant time master Savanti Romero, she traveled back in time to get help from the Ninja Turtles. She ended up banishing Savanti to the Middle Ages, but was forced to pursue him to preserve history. This eventually got Renet and the Turtles to lose the scepter to Savanti, but after a series of conflicts, they recovered it. However, while traveling them back to their present, she lost the Turtles to sixteen-years-prior Tokyo, Japan, due to the mystical time scepter taking matters into its own hands. After six months from her perspective, she was able to locate them and return them to the twenty-first century. In the fifth and final season of the show, "When Wolds Collide, Part One" a hologram of her is first seen in Michelangelo's room. She appears to still keep in touch with the Turtles, particularly Mikey, who still has a crush on her. In the Monstrous Tales saga (consisting of four episodes "The Curse of Savanti Romero", "The Crypt of Dracula", "The Frankenstein Experiment" and "Monsters Among Us!") Renet returns to 21st century New York City, once again needing the Ninja Turtles help in stopping her Savanti Romero from making an unbeatable army of the undead by traveling back to the ancient past, to the time when Dr. Frankenstein began his monstrous scientific experiments.
