Of the four brothers, Leo trained the hardest and he always tries to internalize Splinter's teachings. This diligence, he also tried to transfer to his brothers, but he rarely succeeded. In addition, Leonardo draws from a very highly developed sense of honor, and when other characters share his sentiments, at least in approach (such as Karai and Miyamoto Usagi), he becomes quite close to them. In the future, an aged Leonardo has resigned from killing, after his lover Radical was murdered by Complete Carnage. His revenge killing on Complete Carnage was the final time he would take another life.