Fantasy - Multiple POVs - Young boy develops magic powers + Grandpa needs to escape because of magic powers. Read 2006.

[Megan]

1. Fantasy - Young boy developes magic powers + Grandpa needs to escape because of magic powers. FBI chasing them they get certain body parts blown up (enlarged), sister dies. Boy & Grandpa escape through portals and world hop and they end up in a world that imprisoned them because of it. The grandpa saves the boy by putting him through a portal and grandpa gets stuck for years until he uses toilet paper to slowly create another teleportation device.

Multiple POVS

2006 is when I read it!

[Rainbowheart]

Sounds like something Diana Wynne Jones would have written, but I'm not sure it's one of her Chrestomanci series.

Was the boy a teenager or a younger child? Who or what were they escaping from initially?