I've actually looked at TLR as you have stated here since the end of book one. There was something always underlying about him. My impression of him was one of sadness and bitterness, not hatred or evil. Also, you're hypothesis of the depressive soothing was pretty spot on with my own.
My question is how much influence did Ruin have over Rashek? How many of the atrocities committed were due to his influence combined with TLR's weakened sanity?