My own two cents before the threads is locked for excessive length :
In jimri's mind (and in mine too), the Dark Blood guild has a far looser structure than say the fighter's guild. She does think of it more as a mutual assistance association than anything else. Which means Nytt's almost military approach - it has a bit of an 'I'm higher ranked so do as I said and shut up' feel - feels like he's abusing his power.
Her job as a spy doesn't help there : it means she's not trained in teamwork and will focus on 'what result does the boss want' and do it her own way and tend to disregard his wishes on the 'how' if they don't match her opinion.
As far as what she brings to the guild, mostly two things :
- being a cyrodillic vampire and a good illusionist, she has very little problems passing as a mortal, and an easier time in daylight.
- she also quite good at second-storey obs, breaking and entering and generaly poking her nose unnoticed into someone else's secret. The sort of things a secret guild needs frequently
A third point is that with her official position as an artist and her skill with illusion magic, she can be positively lethal to an 'holier than you' anti-vampire preacher's repute.