Seinfeld has Newman, Dr. Doofenshmirtz has Perry the Platypus, James Bond has Blofeld, Sherlock Holmes has Moriarty, and Batman has the Joker and Penguin. Heck, Siegfried has Roy. All people who clearly are identified with a rival that they cannot overcome, and who always seems to be there to foil their best planning.
In many cases we come to be defined by the battles that we lose or the people and situations that we cannot overcome. Time after time these nemeses come out of nowhere to thwart the best laid plans of our heroes. Their arrival seems unexpected, but we should have known that they were laying in wait the whole time. After all, any nemesis worth their salt cannot let their charge get by with any measure of unfettered success.
Far too often I have seen hero-types with a clear path down the lane (in basketball speak) or with a clear path to the finish line pull up and come to a stop when their nemesis does not appear to try to stop them. It is almost like they either don't want to succeed in the first place or they expect to receive no joy without the challenge of trying to outwit their rival. ... Aww, what does it matter. My nemesis didn't even care enough to show up. ... The result is unresolved angst and confusion. At times, it seems when a nemesis fails to live up to expectations, the hero is forced to take time out of his or her busy schedule to set up nemesis interviews (note that for an application to be accepted, letters of reference must be provided). This whole occurrence just then serves to slow things down and hold the hero back from hero-type work.
So, in closing, if you are a nemesis, please remember how vital you are to the dynamic. Step and do your thwarting job with the appropriate attitude and spirit. Hero work cannot go forward without you. The alternative is to be cast aside and sacked. Trying getting another gig afterwards with that on your résumé.