With the following features.
*Two protagonists between 12-16 years old.
*A boy and a girl (may or may not be related)
*It can be YA.
*Preferably they are not part of a saga.
*Let the adventures lean towards the science fiction side.
*Nothing very depressing.
*Nothing that is after the year 2000.
For example I read Grandpa by James Schmitz AND I really like it. So was seeking something like that.
by Krivus20