Book one in the Barney and Mr. Thomas series

Inventor's Assisatant or Best Friend?

Eleven year old Barney Gile turns into an alligator creature when he's upset. The hardest part of this is keeping it secret. Luckily, the inventor he lives with, Mr. Thomas, can help him. Barney also has another issue. He wants to get closer to Mr. Thomas, but the inventor calls being close to anyone dangerous. Barney never knew why this was until a gun-and-science loving couple starts hunting them down.
Together, Barney and Mr. Thomas go on all sorts of adventures, each one a separate story. Sometimes they're battling the crazy couple and other times they're going to strange places like inside a video game or the Mirror World. They're also meeting people like a clone who thinks he's a goat or a brave girl who might have a crush on Barney.
As they go on more and more adventures, Barney realizes Mr. Thomas is the closest thing he's ever had to a friend. Maybe he's even the father Barney never had, but does Mr. Thomas feel the same way?