Everything about a Leo is, grand, flashy, showy, and dramatic, including their dark side. When Leos are good, they're very, very good, but when they're bad, they're horrid. A Leo who goes to the dark side can be one of the most unpleasant human beings imaginable.
Leos believe the world revolves around only them, and when they don't get respect, attention, praise, applause, and adulation from others, their self-esteem suffers, their darker side emerges, and they morph into a person no one wants to be around either in public or private.
Arrogant, Pompous, and Patronizing
A Leo can act as if they're better than everyone else. They can be scornfully arrogant, disdainfully pompous, and speak or behave towards others in a way that seems friendly but also lets others know they are superior.
Bossy and Controlling
A Leo can demand respect and expect those around them to behave subserviently. They can interfere in what others are doing, bark orders, bully, and expect obedience with no questions asked. When they can't control those around them, they become frustrated and throw fiery temper tantrums.
Self-Centered and Selfish
A Leo can be materialistic, think only about their wants and needs, and be totally unconcerned about others. They may even go so far as lying or manipulating others to get what they desire.
Dogmatic and Prideful
A Leo can hold onto a wrong idea or belief out of stubborn pride. They have little ability for self-reflection and will never admit that someone else could be right or that they've made a mistake.
Jealous and Competitive
Leos want to be the best, the brightest, and most beautiful, and when someone outshines them in any way, they can become jealous and competitive. A jealous and competitive Leo won't hesitate to use cunning, lies, and trickery to discredit anyone they see as a rival.
Ego, Anger, and Revenge
A Leo has a super fragile ego, takes everything personally, and can become hurt and angry at the smallest sign of disrespect. When this happens, they lose their regal composure, become dramatically ferocious, and metaphorically go for the kill. They won't waste time pondering on whether they should seek revenge; they'll only ponder what sort of revenge to take.
Leos have an intrinsic need to be loved. When their need for love is not met, they become greedy and prone to seeking instant gratification. Their great need for the feeling of being loved can lead a Leo to be sexually promiscuous in an attempt to get the love they crave.
An unevolved, immature Leo is like an over-exuberant child who throws temper tantrums, demands attention at any cost, and believes that they are the only thing in the universe that matters. Fortunately, it's rare for a Leo to be so immature and undisciplined that they express all of these darker traits.
An evolved, mature Leo has the intelligence it takes to consciously and actively overcome their darker side and become the confident, generous, fun, and all-around beautiful, shining person they were born to be.
More Than a Leo
Every Leo is more than a Leo. What's written above is based only on generic Leo traits and behaviors; it does not take into consideration the entirety of a specific Leo's horoscope, which can reveal the planets in signs and the aspects that can suppress, or even nullify any of these darker Leo character traits.