system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] In between Anakin becoming Vader and Vader killing Sideous, what did Vader and Sideous secretly think and feel about each other?

This includes film and EU. I would assume Vader hated Sideous in every way. In turn, I think Sideous thought rather low of Vader but liked Anakin. Just my thoughts. 
*Edit: Sidious.
gpt
After a few years Sidious began to loathe Vader as he did not act like a true Sith. He had no aspirations on supplanting Palpatine. This would continue until shortly after the Battle of Yavin when Vader discovered Luke Skywalker. But Palpatine had been intending to replace Vader for years by this time.

Vader genuinely thought of Palpatine as his friend and advisor as well as his Master. He knew his place and became obedient to the letter. But the Death Star  disaster, to which Vader is nearly entirely personally to blame, he discovered Palpatine's burning distaste for him.