It doesn’t matter what you do for a living, even if you save lives or you make the world a better place, you will find bullies along the way. I am not talking about school bullies, my point is about work bullies. If you have worked a little I know you are picturing him in your mind. It’s hard to explain but once you have lived the situation, you’re going to understand it almost immediately.
This bullies are people who use power or some other advantage (it could be an SLA or some contract between his company and yours). They try to intimidate you and demand things. They use your fear and inexperience against you. They want things now and tend to be pushy. I am going to talk about what have worked for me, maybe doesn’t necessarily apply to your situation.
The first thing would be don’t back off. I am not telling you to go look for him and have a fight. Just don’t back off. If you do this they will gain more power, that’s the position where they want to be. They want you to feel the fear, so they gain control over you and you do what they want. Try saying No, think about reasons. Don’t play the same game, be reasonable, but say no.
It’s normal to look for help. Look for more experienced teammates, they have fought bullies, they know what to do. Also look for allies, they might help you saying No. One of the weapons bullies have is: I am going to escalate this (tell your boss). This weapon is useless if your boss already knows.
For me the next step was: fight back a little. I am not encouraging you to start WWIII, just fight back. Ask him for stuff, demand thinks. Try doing him the same stuff he does. Sometimes the best defense is a good attack. Don’t be a bully yourself, just a little.
The next thing might seem weird, but eventually happened for me. Bullies eventually go away. They enjoy bullying people who don’t stand up. They like easy things. Once you put a little resistance, you’re not a good prey anymore.
Bullies help you a lot. Once you stand up, it’s hard for other bullies to nag you. Don’t go to the other way, don’t be a bully. It’s really important for anyone to stand up.