Read Grendel by John Gardner. It's a retelling of the Beowulf myth from Grendel's point of view, only using it as the basis to explore modern philosophical viewpoints. I'll sketch the evolution, as the plot obviously isn't a spoiler, and the point of the book is the mental journey Grendel goes on:
Grendel starts off with only animals for company, and realizes he's the only intelligent thing around, so comes to a kind of solipsistic/nihilist view: Nothing means anything. He meets the dragon from the Beowulf tale, who further tries to convince Grendel of a dumb, mechanistic universe, where everything is determined by cause and effect, nothing more.
Then he meets humans, and at first he hates them for their boasting and pretensions to grander things, but is drawn to their stories about God and heroes, which almost make him believe in an order and purpose to the universe.
He tries to join them, but is attacked as a monster, so he decides he and the humans can give one another meaning: He can be the monster the humans see themselves as opposing or better than, the monster that inspires them to make the heroism of their stories a reality.
This backfires though when Beowulf arrives, who is physically a hero but who doesn't believe in heroism -- merely in might makes right, the same kind of nihilism Grendel is trying to escape.
It's an engagingly written book, with many great turns of phrase ("I create the whole universe, blink by blink"), though the language is very modern, which might throw some people expecting a more 'fantasy' style. The dragon, for example, tries to tell Grendel about molecules. For video game fans, I strongly suspect the style heavily influenced Bungie's fluff for the game 'Destiny' -- it has that same mix of academic terminology and magic.
It's also a quick read, at under 200 pages, so it's something you can go back to again and try to puzzle through for meaning of your own.
