There were a few things that seemed a little too convenient and contrived in this chapter:
1). Riden noticing the large print label with the word WARNING on it only
after giving the potion to Tess. *I can let this one slide though, because that does sometimes happen.*
2). The fact that the healer passes by their (presumably) secluded cabin just as Riden is coming out of his first vision. And the idea that the healer is able to correctly diagnose Riden as being part Dremora simply by Riden telling him about his vision which, to my recollection, was about a blue light healing Tess and had nothing to do with any sort of daedra.
3). Riden’s ‘sudden’ recollection of a family tree once read that identifies him as being part Dremora. That is definitely
not something that one would be likely to forget!
4). There is NO WAY that a guard of the City Watch gripes about a lack of professionalism in a
note that he sends to the assassin he has hired! That one made me laugh, but I don't think that's what you were going for.
I think the conflict that you have between Riden and Tess (will he or won’t he quit being an assassin?) is the strongest thing you have going in this story. It draws us in far more than your story arcs concerning a war with the Dark Brotherhood and Riden having powers because he is part Dremora. Why? Because the conflict between Riden and Tess feels genuine. Your version of the Dark Brotherhood doesn’t feel real simply because there is no way that the DB sends a letter to the man who just killed their listener (begging the question of just how they came across that information. Although I guess I shouldn’t be surprised with the number of incriminating notes floating around Cyrodiil in this story

). Equally outlandish is the fact that they address the note to ‘Riden Snow
and family’.
Give us more of Riden and Tess. That’s who we care about, and that’s who we want to root for!