So in this world, everyone gets some kind of power at age 12. Most powers are common and not so unique, while others are rare and unique.
The main character is called 'Splitter', and that's a running joke throughout the series because nobody ever knows his real name. When he turns 12, he goes in front of a panel of wise elders to judge the use of his power. He let's out a ball of light from his hands and splits a rock in two. Not literally, it splits the rock into an equal positive and negative half. After a few seconds, it combines back into it's normal form, since both halves are equal.
The panel decided that he will use his power to split people into their good and evil halves, and then they must fight. If the good half wins, then they are truly good. If the evil half wins, then he must defeat the evil half. He starts off with a small, specialized sword. Whenever he defeats an evil half, that sword grows larger. Much later in the series, that sword is gigantic and awesome. :P
A turning point comes a few years later, fast forwarding. His best friend asks him to split him. He does so, and the evil half wins, forcing Splitter to defeat that evil half. At this point, he questions the morality of using his power, and wonders if he is truly good or evil. He gets frustrated, staring into his reflection in a body of water, so he uses his power and pounds the ball of light into his self. Much to his surprise, his evil half escapes quickly. This sets the theme for the next 2 seasons. His evil half earns the name 'Stitch', because on top of being able to split people, he can stitch halves back together to make a stronger evil side, including into himself.
Later on, he comes across a girl named Sophia. She keeps begging him to split her to see if she's evil, but he keeps refusing. After many instances of this, he gets fed up and does it. She ends up splitting into 2 equally good halves, named 'So' and 'Phia', until much later on when he gets the stitch ability to bring her whole again. Also, at first, she is too young to have any kind of power.
A while after that, he encounters someone else that joins the party, named 'Ria' (Air backwards :P). His power is that he can make a circle with his finger, then blow into it. A whirlwind comes out of the other end of it. Later on, he learns to do the opposite to create a vortex that sucks everything in. Ria is a thief, but he only does so to survive and help people in need. He ends up convincing Splitter to split him. In doing so, the two halves, good and evil, are actually equal. After a fight scene ensues, they both end up combining back together automatically, since they're both equal.
Without revealing much more ideas, that's what I got so far. :P
