The Kung Fu Ninja Troupe

Not necessarily a single character but rather an entire crew of them. Here's a group of young Kung Fu Ninjas in training (I know, Ninjas don't do Kung Fu). The trainees consist of mostly kids, abducted or kidnapped by the guys who run the group. The "admin," say, is an old man with a funny moustache whose motives are unclear. He abducts kids, makes them "tour" with him to strange places and practice martial arts, and won't let them leave. He also equips them with dangerous ninja swords ... Plastic swords. But they are surprisingly damaging.

Some of the trainees want to escape, while others actually enjoy being with the crew and would happily stay.