Perfect age range for dystopian novels. You can start with Animal Farm and Anthem for the 10 year-old(s) and the one closer to 13 can read 1984, Brave New World, and Fahrenheit 451.
There's also the Lord of the Rings novels and the works of the greater Legendarium (Silmarillion, Children of Hurín, etc.)
The books I wish I read as a kid were the Count of Monte Cristo, the Fountainhead, and Atlas Shrugged, all of which I had read at the cusp of adulthood despite having the aptitude to understand the works as a teenager.
There's also the Lord of the Rings novels and the works of the greater Legendarium (Silmarillion, Children of Hurín, etc.)
The books I wish I read as a kid were the Count of Monte Cristo, the Fountainhead, and Atlas Shrugged, all of which I had read at the cusp of adulthood despite having the aptitude to understand the works as a teenager.