A few points, aimed at nobody in particular:-
1) Respect
I believe that respect is, to a certain extent, due to everyone. I try to treat everyone with whom I work with respect. However, More than the basic needs to be earned by everyone. Nobody gets it as a matter of course, simply because they have a certain number of gold bars on their arm, or a different colour name tag. And if they behave with indifference to others, or treat them rudely, that respect rapidly gets eroded.
2) Behaviour
I have never claimed that the fault lies on either one side or the other of the F/Deck door. There are CC who are wonderful, get on with the job, and are more than happy with the job that their position in the team confers. There are some, I can well see, who would prefer to think of themselves as "Alternative Captains". Similarly, some F/Deck crew will ttreat CC with respect and as valued members of the team, others who are condescending, arrogant
pr@ts. This problem is, partly, a result of the attitudes of the latter in each category. If some are misbehaving, do not adopt the hard attitudes to all that I have seen in some posts on this thread.
3) Training and Corporate Culture
If CC are being taught to behave as if the F/Deck crew are a totally different team, if SEP's don't even teach them how to operate seats on the flight deck, if they don't understand the chain of command aboard an aircraft, then something is very seriously wrong. The company's Flight Safety Officers/Managers need to get involved as a matter of urgency, because this is clearly leading to a breakdown of teamwork on board the aircraft, and that is DANGEROUS. Company Management also needs to get involved, because the corporate culture is being eroded from inside, so that office politics is taking over from what should be the first priority every time - FLIGHT SAFETY.
Finally, I personally would make every effort I can to re-establish a good working relationship with an individual with whom I find working to be "difficult". If that failed, I would, down route, read the Riot Act. Back home, I would take the issue to a suitable neutral intermediary, like a Flight Safety Manager. Last resort would be to refuse to fly with that person.