The Question and Answer section for Grendel is a great resource to ask questions, find answers, and discuss the novel.
Grendel hates the obvious happiness in Hrothgar's hall. He is twice attacked by humans and made invincible by the dragon's magic. He is not accepted by the humans, thus, he makes it his work to kill them.
When Grendel first meets Hrothgar's men, he is overcome with curiosity, as are they. If fact, the men believe Grendel to be a tree spirit and attempt to feed him. It isn't until Grendel tries to verbally communicate with the men that they become...
The dragon tells Grendel that he is all knowing and higher evolved than all living things. He believes the theories of humans to be nonsensical, and the Shaper to be no more than a manipulator with impeccable skills in presentation.