This is my raichu... no name? I dunno! It's a WIP

He procured his peculiar eye colour when his trainer tentatively tried to evolve him from a pikachu; during the evolution, the trainer changed his mind and threw a rock at the shining form to try and stop the evolution but instead it knocked the poor thing out! The hit from the rock was close enough to his eye to cause a simple reaction of hemosiderosis which, in turn, caused iron to deposit from blood products and THUSLY turned his eye blue. (brief research I did ages ago, this is all I can remember about heterochromia so if my info is off, oh well! I'm not a doctor and I don't claim to be. I just like having reasons for "cool looking" eyes).

The trainer abandoned him and he was captured a week later by a Team Rocket member. Now he finds treasure and junk :P