[Boromir88]

That would include contempt for his sidekick, yes?~Nerwen

I wouldn't doubt it. The servant is expendable, once the Master has no more use for the servant...well then the servant will be dealt with in good time. Much like what Sauron did to Saruman:

But they shall help to rebuild Isengard which they have wantonly destroyed, and that shall be Sauron's, and there his lieutenant shall dwell: not Saruman, but one more worthy of trust.~The Black Gate Opens

Sauron no longer trusted Saruman, and seeing as Saruman was no longer any use to him, he was going to get canned.

Where I'm going here, is it's hard for villains to get along, especially when you have two who want to be "Dark Lords." You can't have two Dark Lords can you? Well, one wanted to destroy everything, the other one wanted to dominate/control. Sauron was drawn to Morgoth's service because it was the best way to further his own plans. He probably figured can't beat him, it'll be better to play along and join him.

Maybe Sauron figured out, Morgoth was a nutcase who wanted to try to achieve the impossible...so Morgoth would end up pretty much electing the path to his own fall and Sauron would have free reign. Anyway, I don't think there was a brotherly love between the two, they were both using the other to further their own gains. I think that is seen with what Sauron does after Morgoth is out of the picture:

Sauron was not a ’sincere’ atheist, but he preached atheism, because it weakened resistance to himself (and he had ceased to fear God’s action in Arda)...~Morgoth’s Ring, Myths Transformed

This is referring to Sauron trying to make Melkor worshippers (example, The Numenoreans). But why? It wasn't because he admired his former boss, it was because he realized it made his job easier.

I think Saruman and Sauron's relationship in the 3rd Age parallels the relationship Sauron had with Morgoth. Both were attempting to use the other to further their own benefit:

"We may join with that Power. It would be wise, Gandalf. There is hope that way. Its victory is at hand; and there will be rich reward for those that aided it. As the Power grows, its proved friends will also grows; and the Wise, such as you and I, may with patience come at last to direct its courses, to control it. We can bide our time, we can keep our thoughts in our hearts, deploring maybe evils done by the way, but approving the high and ultimate purpose: Knowledge, Rule, Order..."~The Council of Elrond

Backtracking a bit to this...

Just because the goal is unattainable doesn't make it less evil, in my view.~Kuru

But it does make Sauron more practical...and if practicality is one trait that goes into being a good villain (look an oxymoron! ) then Sauron certainly had the edge there.