1. Do not give them the time of day.
Difficult people are unreasonably self-centred and will only interact with you on their terms–which is necessarily negative.
If you are in fact more reasonable than they are, you must not resemble them in their speech. You must not speak sarcastically, pessimistically, sceptically, cynically, depressively, passive-aggressively, angrily, biasedly etc. even with other people in ear shot of them.
Speaking like this will make you appear weak–like they are.
When you speak respectfully, optimistically, open-minded-like, unassumingly, happily, assertively, confidently and neutrally they will most likely have nothing to say to you because conflict alone is their prerequisite for interaction with you. Being friendly with you means they would have to go outside their comfort zone which they do not have the courage to do. If you interact with them outside of necessity, you are very much involved in one another’s lives, so you must naturally function perfectly well without them, in other words, independently.
2. Let them be.
Determine as early as possible whether the difficult person could be more reasonable than they are.
It is likely that they are not open to the idea of being friendly with you because their values are opposed to your values. And if their values are necessarily inferior, they lack real ambition. You must usurp this position of command meaning with time you will accumulate greatness in and of yourself whereas they will wallow in self-loathing. This is an inequality that is just.
When they behave unreasonably, there is the temptation to explain to them why they are in the wrong, but this is potentially patronising on your part because they may be well aware of why they behave as they do and to what effect. You must save yourself time and energy and ‘punish’ them appropriately meaning without disappointment as stated above.
They want to be rewarded in life, but so long as their own unconstructiveness cannot bring this about, you must never presume that rewards will make them happy. By this you will less likely tolerate their indignity meaning you won’t give them more than one chance to make amends.