What does Grendel's relationship with nature -- the ram, the sky, grass, the doe, the baby bird, owls, and wolves -- reveal about his own personality?

Grendel's relationship with nature is purely personal; it relates to human nature, or the respect of one living thing for another. Grendel's father was brutally murdered by "humans," Grendel and his family are different, they're something to be feared, and they're something to be hunted; just like the animals in nature.

Grendel sees no good or bad, he sees survival. He understands the actions of the predator (ie. wolves), and he appreciates the "new life" of a baby bird, and the life giving ability of the doe. He cannot understand Beowulf or the others because he doesn't understand the actions of those who don't live in the world of survival or appreciate the ways of life such as living and dying. To be cliche-- the circle of life.

Grendel can appreciate what he understands, but he has no comprehension of those who want more than life, that is those who want to conquer and change the world around them according to their own beliefs.