At one time, this Leonardo was similar to his dimensional counterpart. However, the mysterious disappearance of his brother Donatello and the death of Splinter led to the deterioration of their family. A rift formed between Raphael and Leonardo, who disagreed about whether they could have saved their father. Unable to tolerate each other's presence, the two parted, leaving Michelangelo alone.
In the thirty years that followed, Leonardo remained alone, fighting against the Shredder and the Foot Clan along with April's resistance. He became heavily scarred and stopped wearing his mask, perhaps because he began wearing sunglasses.
This changed when a younger Donatello from another dimension was sent into the dystopian world by Ultimate Drako. Upon discovering that Shredder ruled the planet and his brothers had gone their separate ways, Donatello brought them back together. Leonardo and Raphael nearly launched into another fight upon seeing one another, but were interrupted by Donatello. Delighted to see his brother again, Leo eventually agreed to help Donatello destroy Shredder once and for all.
During the final conflict with Shredder and his forces, Leo fought Karai. He managed to defeat her, but as he was about to finish her, he was distracted by a Karai Bot. Karai took the opportunity to strike him down from behind, killing him.
His death served as a motivation for two of his brothers. Raphael, enraged at his brother's death, unsuccessfully attacked Karai and was himself mortally wounded. He died crawling towards Leonardo's body, calling out for him. Donatello was further spurred on to kill Ch'rell, avenging all three of his fallen brothers.
- Due to constantly wearing sunglasses, it was assumed by many that dystopian Leonardo was blind. However, TMNT4Kids (the 4Kids Entertainment-to-fans liaison) said that the script never mentioned him with any kind of vision impairment, only "scarred".