Caravaggio

Caravaggio is the fictional 5th long lost brother of the Turtles, who was known to be the 3rd youngest of Leonardo and Raphael, and 3rd oldest from Michelangelo, and Donatello.

His bodily and facial features clone that of his eldest brother Leonardo, hinting that Caravaggio may have been Leo's twin brother.

Caravaggio due to have being separated since birth, never officially knew he had siblings until 2008, but was also known to have a really dark past of training too much to the point that he permanently became damaged in 1998, while under Mistress Kayushi, despite this past, Caravaggio was still shown to be able to handle himself on his own but lacks defense, due to his failing body.

Personality
He has both the personalities of his big brother Leonardo and his little brother Michelangelo. He is the second swords turtle of the team who as well carries 2 Katana's with the help of training from both Master Splinter and Leonardo, Caravaggio learned how to attack with great speed and aggression.

Skills
Caravaggio is known as the Co Engineer of the team. He assist Donatello in the construction of new equipment and weaponry for future use.

However Raphael who seems to be Jealous of Caravaggio gathering all the attention bully's him behind Leonardo's back Including while he was away during his training of becoming a better leader, however this was shown to be false, as Raphael has been doing this as a tough love kinda relationship in order to wip Rivera into shape, during the time.

Resemblance To Leonardo
Caravaggio at the time of his reunion with the turtles in 2008 bared a huge resemblance to Leonardo, and also wielded 2 Katana/Naginata blades. They also contain similar bodies, and heads, resulting into them might being actual twins, but this was not yet or ever was stated at the Time of the reunion or Noratic Crisis.

The way that the 2 are told apart is by head band, Caravaggio's was often Dark Tan, while Leonardo's remained blue.

Fighting Style
During his separation from the Turtles, Caravaggio spend 10 years in martial arts, and became a skilled swords turtle in England. However his trainings would also become his major downfall as in 1997, Caravaggio eventually came under the wing of mistress Kayushi, Caravaggio was trained so much to the point that his shell cracked and he became broken to the point that he lost his ability in defense.

Although his attacks are Flawless even after this tragic event, Caravaggio's broken body expressed difficulty in dodging some objects including giant monsters, he also lacks defense, which also makes him vulnerable to attack, this problem is mostly caused by not only his broken body, but from also conducting too many offensive tactics.