The Sun is the essential sense of self-what you are behind the facade/appearance of the Rising Sign. The planets that aspect it are the outlets of its energy and work as a modifier. But the Sun/Sign is you.
Where this takes place in your chart is very important.
First: Second: Third: Fourth: You identify with your home. Strong need for a home base. Fifth:Draw identity as a creator: Sixth; Seventh: You draw your identity from the groups you ally with. Your basic approach in life is to look to someone else to make you you. You feel you need a partner of some kind. Eighth: Ninth: Tenth: Your personality is your career. Public figure, anyone? Eleventh: Your hopes and wishes come from the essential part of your personality. You may identify with a group. Twelfth: Who you really are as a person may not be apparent at first glance, hidden behind isolation.
As for the Sun in various Signs: there are separate pages for that, so that will not be discussed here.
The Shadow Side: The Shadow side of the Sun: egotism, self-centeredness, pomposity, and the need to be the center of attention at all times.
The Sun never retrogrades, so it’s energy is always directed outwardly towards the world. Of Course, this is because retrograde is based on the appearance in relation to the Sun of a planet.