I'm starting to feel that my character is now ready for the production. There are theories that Grendel used to be a rampaging berserker or just a serial killer. People back then used to fear and respect nature much more, so there is no wonder that someone more powerful then simple human for them seemed to be supernatural and its description turned into a real monster from the woods.
Separate parts will help me not to loose the detail of every single part. Right now I can draw this creature in any pose and I feel absolutely familiar with its every detail. I merged Celtic ornaments, parts of trees and human anatomy into one thing and now I have my version of Grendel.
And here's also quick video of my work process.