I'm at the end of the second year of a phd in engineering. My project is going well: I'm involved in an international project and I submitted 6 journal papers and 5 conference papers.
The problem is the relationship with my main supervisor.
I have two supervisors. I'm working really well with my co-supervisor. He has always showed interest in my work and in me as a person. He provides me accurate revisions on papers, reports, oral presentations, and so on. At the same time, he leaves me free to direct my project as I prefer, as long as my work is coherent with the topic of my thesis and with the objectives of the project we are involved in.
Things are different with my main supervisor. He couldn't care less about my work. I hardly remember the last time he gave me any guidance or even corrected one of my papers. He requested I help other phd students and provide him with didactic material for courses.
I spent most of the first year helping another student, understanding that the work would be part of my thesis. At the end of the year my supervisor asked me not to inform the phd committee of my participation in that work, because it could damage the evaluation the student.
This year, something similar happened. One of his M.Sc students could not finish a job in collaboration with another professor. Now he wants me to finish that job, because he doesn't want to offend that professor. The problem is that he's not even in my research group, I don't have any experience with the subject and this is slowing down my work, as this job should be completed by the end of the year. My supervisor also gave me other extra work, telling me not to tell the other supervisor and not to add his name in my works.
The worst part came when my co-supervisor proposed me a postdoc position. My main advisor became arrogant, telling me not to f**k up things (litterally), that he's the boss and that if I want to go on working in research I have to stay with him.
I tried many, many times to talk to him, but his answers are always the same: "don't do s**t, remember who's the boss here".
Normally, I wouldn't ask advice from random people over the internet, but I really don't know what to do. Talking to him seems completely useless. Maybe I should talk to the other supervisor, but I'm not sure he would support me against a colleague. I'm afraid I could end up even more isolated.