There's nothing you can do for me. The wound is fatal. I will die. But there will be others. Unlike me, they have come to destroy you. 

The Yeerks are parasites. They must have a host to live in. On Earth their hosts are humans. They enter your brain and take over your thoughts and feelings. These hosts are called 'controllers'. They can be anyone, your family, your friends. Earth is their next target. 

Sometimes children can accomplish amazing things.