The Shaper's Art

There's certainly a difference between how all of the different characters perceive and retell events, and how it defines the character, both objectively and in the eyes of the other viewers. For example, when Grendel tries to present the beauty of the juxtaposed life and death, the reader can see that the moment clearly shows Grendel's capacity to express creativity and love. However, in his haste and passion, he blows open a door and scares the Thanes. The Thanes tell a different story, and use the same setting to shine Grendel in a negative light. Due to his long life, Grendel has seen the rise and fall of many kings. Because of this, he has seen the terrible atrocities committed by man, and although the music stuns him, he is conflicted about the inaccuracy of the stories. This can be seen at an extreme level when Grendel meets the dragon who knows both past and future. The dragon seems to be jaded by this knowledge. Not physically -- he still is very active. He is jaded in the sense that he doesn't have the will to stop these terrible things from happening. He knows of deaths that will occur, he even gets meta when he references that Hrothgar's age will later be referred to as the 'Dark Ages,' but he doesn't even attempt to change what will happen. After all of his years, he does not even dignify the concept of thinking differently about events.
This relationship implies that the longer a being lives, the less liberty they take with modifying the past. This would imply that the more mature beings, with the all-seeing dragon as the epitome of maturity, respect the events that occurred and as such don't change them later. Although it might suit the Shaper to spin a tale of intrigue, the older beings know that the real value of memories comes from their stability. Men should not take liberty with the past.
However, if you're an artist trying to make a quick buck, you should take EXTREME liberty and make radically awesome stories. No line.