At right: The Emperor from the Hanson Roberts Tarot Deck.
I have never liked The Emperor. He and the Hierophant have always annoyed me and I see them both in the same light. But, then, I've always been one of those uncomfortable with authority and with the church. Not that I'm equating those two... entirely.
For me, The Emperor represents The Powers That Be. At worst he represents someone/thing that is smug, self-important, and possibly invested with too much power. It's difficult for me to remember that not every official is bad and that I shouldn't be so prejudiced. I try not to assume, when I see The Emperor, that there is some negative force at work.
The Emperor can represent individuals or institutions. He might represent marriage (yup, that's an institution), a large company, a government office, the church, a belief system, a school or educational system, the medical field in some capacity, or the law (specific law, police officer, judge, lawyer).
I rarely get much from the symbols held by or surrounding The Emperor. He reminds me a bit of the Two of Wands who I sometimes also see as somewhat smug and invested with too much power/things/money (than he knows what good to do with).
For the most part, when The Emperor comes up in a reading I feel as if there is a message to the Querent about seeking some kind of help (medically, legally, etc.) or finding some resolution with a problem pertaining to the marriage, legal authority, education, or with a medical issue. What The Emperor is representing is usally apparent within the context of the reading.
The Emperor may also come up to represent responsibility. Or the need to take some! I often see this card when someone is asking a question like, "I don't know what I'm going to do, I feel lost/helpless/confused." If this card comes up I remind them that they may need to ask for help from either the state, their health care professional, a mental health care professional, or from a friend or family member who may be in a position to help them.
I also sometimes see The Emperor as an admonishment to be more disciplined and logical and to take charge of a situation.
In the negative, The Emperor may be pressure from a figure(s) of authority such as judgmental parents or a domineering spouse. Any demanding, unforgiving, critical influence might be represented through The Emperor. Even a person's own relentless compulsions may be shown through this card.