K.A. Applegate

The Animorphs Series

Characters:
Cassie,  a girl who is an animal lover and works as a vet.
Marco, a guy who is not very serious and always makes jokes.
Jake, a very serious guy who makes all the decisions for the team.
Rachel, a very ferocious girl.
Tobias, a hawk who is not very expressive.
Ax, an alien from outer space who is smart. 

Summary: In the Animorphs series of books the characters listed are a team who fight the Yeerks. The Yeerks are slugs that can  enter a body by the ear and take control of it. The kids fight them by  morphing into different animals. They can turn into any animal they touch. In all of the books in this series, the kids fight the Yeerks. Sometimes the books are bizarre and sometimes they are cool. They have every kind of voyage imaginable. In some of the books, one of the kids gets infested by Yeerks. All sorts of battles occur. If you want to know more, you should read the Animorphs.

Did you like it? Yes, these books are full of action. They pull you into the story and make you want to read more.