DIsclaimer: Although I will use Christian religious imagery, this idea should also be useful to non-christian people, if they treat the concept of a "thwarting demon" as a metaphor for a "mental obstacle" or even simple bad luck.
Although your Thwarting Demon (TD) may present itself differently to how I perceive mine, the effects and situations should be recogniseable.
I first gained a hint about what I was up against when a friends dad, on hearing about the "accident" where a stolen metro had just destroyed my parked car, which I needed to do my new contract, remarked "You are the most unlucky person I know".. I realised with a start that yes, I did seem to have an awful lot of "luck". This was some 30 years before I was ever to fully understand my situations, but I did understand that not a lot seemed to be working for me at the time.
As I wrestled to survive in a world that nearly everyone else but me seemed to "secretly understand" (that couldn't be right, it's more likely I have a paranoia I, and many others, told me) I realised that on some days or even sets of days, NOTHING I DID WENT WELL.
I compared myself with others, I reviewed my personal drives, procedures and morals etc, and came to and understanding that there was no discernable commonality, my experience was that some days, no matter what I attempted, I would fail. OF course, I assumed this was self fulfilling prophecy, or some other poor mental attitude first, BUT after a decade or so of hard work trying to become more "productive" I yielded to the observation that the phenomenon of my persistent failure to succeed had an "X" factor that operated outside of my control. On some days the confluence of events that would often attend my failures seemed so unlikely, that it really seemed like a malevolent entity was delliberately messing with my circumstances.
For me the breakthrough and real fight back started when I saw the thwarting demon in my imagination.
It is pretty non-descript really, but it stands (on hot coals of course) behind a bloody great control panel filled with switches, dials, levers, and the odd view screen. He has an unreasonable quota of living people to torment with his thwarting panel and he rotates himself amongst the people on his list, sometimes focussing on one of us for a long time, sometimes he gives it up fairly quickly.. HIs goal is to frustrate you enough that you either become miserable and self focussed enough to either do something stupid or evil.
And omigod, it used to work so well on me, the only coping strategy I initially found for a long time was to just sleep it off when nothing would go right, and if it still wasn't going right when I got up, then go sleep some more.
And that gentle reader, is what this rambling screed is really about, finding a coping strategy. I will be honest, as a J.C. fanboi I have a number of religion based ideas and strategies for dealing with demonic entities, which seem to help me personally, but I suspect that the (probably majority) non-christian readership will also contain people who have experienced anomalously consistent periods of failure (thwarting) at such a level that they like me "needed to take action to get some relief".
Or am I on my own in this aspect of the experience?