After the Kraang drama on the people of NYC, Shredder's attack on the four brothers, Splinter, April and Casey and with Leo being a coma due to Shredder; the four brothers and two friends had to stay at a farm house that April used to live in with her parents when she was young.
It took 3 months for Leo to finally wake up, but once he did, he couldn't stop. He was seen mostly training despite having badly damaged his knee/leg. Sometimes, he'd meditate under trees and in the woods close by - others - he'd try to train with Raph only to fail because of his stupid leg. He'd get frustrated by it often, feeling useless and like a failure when his stupid bone stopped him.
One early morning, you saw Leo sat out on the porch on the bottom step, his one wooden crutch leant up against the railing as he looked out on the mornings sky before sighing as his head lowered; the tails of his bandana draped over his shoulder.
Everyone had something to do when they woke up. Mikey took care of the chickens. Donnie and Casey worked in the lab and created new and helpful mechanics. Raph did as he liked, mostly training; and April went on the occasional shopping routine with Casey. What did Leo do? Sit there and look pretty?... that was all he was good for, and it sucked.