First Date by Lucas Flint

Alex Fry (Beams) has a great life. He's a famous sidekick, works for one of the best superheroes in the world, and is even dating the girl of his dreams. While Alex can't publicly accept the praise and accolades his sidekick persona receives from fans, his life is good nonetheless.

That is, until he becomes the target of the most infamous assassin in the world, whose presence in Golden City forces him to go on the run. Even with the arrival
of a new superhero to protect him, Alex's life is still turned upside down, forcing him to remain in hiding to avoid getting killed.

Now Alex must catch the assassin before the assassin finds him. If Alex fails to defeat the assassin, then everything he's worked for will collapse.