It is hard not to have at least a little sympathy for the Devil on Supernatural, as his portrayal as a misunderstood soul, whose only sin was loving God too much can be believable at times.
This is true especially now that God has released his sadistic side upon not just the Winchester boys but creation itself. Daddy issues aside, Lucifer has done some pretty terrible things. Things that even he admits are worth being locked in a cage for all eternity for. So will the real Lucifer please stand up? Is he misunderstood or evil incarnate? Let's recount the best and worst things that Lucifer has ever done on Supernatural.
Best: Alternate Lucifer Is An Environmentalist
So, when people think of Lucifer, they probably don't imagine a tree-hugging, save the world kind malevolent entity. Mainly because our first imagining of him involves more of a scorched earth vibe, rather than planting a tree in the park sentiment. In season 5, in an alternate reality where Sam says yes to be Lucifer's vessel. Dean finds himself having a conversation with Lucifer in Sam's body about how Lucifer admires the planet earth for its beauty, swearing to never harm God's masterpiece.
Worst: Snapped Future Dean's Neck In Front of Present Dean
Right before the conversation about how he admires God's handiwork and a love for the planet begins, Lucifer, in Sam's body snaps the neck of 2014 Dean, right in front of 2009 Dean and does so in the most nonchalant of ways. After killing Dean's future self, Lucifer dares to attempt to gain sympathy from Dean by telling him the story of how he fell from God's good graces by renouncing humanity in favor of loving God more. Thus, leading to his imprisonment. Dean doesn't fall for Lucifer's lies, insisting he will kill him someday.
Best: Helped The Winchesters Take On Amara
Whether it was because he understood the greater threat or because he felt it was a family matter that needed to be attended to, Lucifer, put aside his ego and his disdain for God and the Winchesters to fight beside them against Amara.
During the battle, he even showed a form of camaraderie with God, trying to save him from Amara's attack by stabbing her in the back with a spear. Sadly, the rescue attempt failed and he was thrown to the side by his now vengeful and angry aunt.
Worst: Killed Pagan Gods
When the pagan gods met to try to work out a way to stop the impending apocalypse in season 5. They soon found themselves outmatched and overwhelmed by the archangel, after Hermes, attempting to save his skin alerts Lucifer of their location. After arriving, Lucifer appears quite cordial with Hermes before revealing his true disgust by snapping Hermes' neck. He would have killed all the pagan gods if not for Gabriel's intervention. Unfortunately, Gabriel ended up sacrificing his life so that the Winchesters and the remaining pagan gods could escape Lucifer's wrath.
Best: Loved His Archangel Brothers
Lucifer holds ordinary angels in the same contempt as he does humans; believing them to be lesser, unnecessary creations whose lives are meaningless. Though, when it comes to his archangel brethren, he has a real soft spot. In Lucifer's first encounter with Gabriel, he tries to lure him to his side, when he is finally forced to strike down what he believes to be the real Gabriel, he finishes the job but appears remorseful at the loss of his brother. Lucifer, also, showed a brotherly love towards Michael but holds a deep resentment for his supposed betrayal.
Worst: Summoned The Four Horsemen
After Lucifer's release from his cage, which breaks the seals setting off the apocalypse, his lack of regard for life is clearly on display when under his command the Four Horsemen of the Apocalypse bring devastation to the earth.
War quickly turns a town against each other, pestilence begins his plan to unleash the Croatoan Virus, a disease that would exterminate the human race. Famine unleashes hunger upon civilization and Death creates a zombie outbreak. The Four Horsemen of the Apocalypse were eventually defeated by Sam and Dean. Though, unknown amounts of individuals died during their time on earth.
Best: Saved Castiel From Angels
After learning that the alternate Michael is attempting to come to earth, Lucifer breaks free from his alternate reality prison to find Castiel in battle with three angels, who are out for his blood. With the understanding that a greater threat awaits them, Lucifer kills the hostile angels. When Castiel attempts to kill him, Lucifer blocks his attack, though sparing Castiel's life as he tries to relay the danger both are in if the alternate Michael breaks free from his temporary captivity. Sensing Lucifer is being honest, Castiel casts aside his differences with Lucifer.
Worst: Tortured Sam In The Cage
Lucifer's cage was designed by God to only house Lucifer in the darkest depths of Hell, but in season 5, Lucifer is again re-caged but this time he takes Sam and Michael with him. With the time in the cage going by slower than time on earth, Sam was tortured for over 120 years before his body was freed by Castiel, though his soul remained trapped within. Death finally freed Sam's soul from the cage, reuniting it with his body. Sadly, Amara's reappearance resulted in haunting memories of his time in the cage being returned.
Best: Tried To Bond With His Son
Upon first meeting Jack, Lucifer tries to entice him to go on a journey with him beyond the stars, traveling to unknown space. Though, feeling uneasy about his father's true motives, Jack refuses. When Castiel tells Lucifer what his son really thinks of him, Lucifer resurrects Sam as a gift to Jack, in the hope that he would forgive him. Yet, like always, his true ambition takes hold, as he uses his son's grace to gain ultimate power. His plan fails as he is finally defeated by Apocalypse World Michael.
Worst: Tried To Kill Gabriel
The saddest part of Lucifer is the fact that even to those he truly cares about, he can never put them before his ambition. When his sanctimonious pity party was rained on by Gabriel, Lucifer warned him to stand aside and he would let him live, but, when Gabriel refused and attacked his brother, Lucifer killed him without mercy. What Lucifer didn't know was that it wasn't the real Gabriel he had murdered. Though, believing it was, Lucifer sincerely grieved for the loss of his brother. Yet, the loss was not great enough for him to change his ways.