Savagery comes in many forms and guises so you could work that into your thesis. Generally speaking, the thesis should basically lay out what specifically it is you will be talking about. Not just...I'm going to be writing about savagery in LOTF, but something that says, savagery in LOTF happens in three critical places within the story. Or you could talk about physical, emotional, and spiritual savagery with examples.
Hope that helps some