Archvillain by Barry Lyga (author) (US edition)

Sometimes it’s good to be bad.

Kyle knows exactly where he was the night Mighty Mike arrived: sneaking around behind Bouring Middle School, preparing his most ingenious prank yet. Which is why he couldn’t tell anyone where he was. Or what he saw. Those lights everyone spotted in the sky weren’t tiny meteors. They were a strange plasma that bathed the entire sports field – including Kyle – in alien energies. And then Mighty Mike fell to Earth… Other people think Mike is just some super-nice kid who stumbled into the field, lost his memory, and decided to start rescuing kittens from trees. But Kyle knows that Mighty Mike is really an alien. And he’ll do anything in his power to stop him – even if it means becoming an Archvillain!