In the MCU, Thanos claimed to be motivated to kill to create balance in the universe, and that there were not enough resources to support all life. This is total crap in my opinion because he could have used his power to develop more planets to be viable to support life, or when he got the gauntlet he could have doubled the resources in the universe, or made half the populations sterile, or made everyone into cosmic beings that don’t need to eat and can just live in space, or any other number of things that don’t involve killing trillions of people. He also would not have said that he was going to enjoy watching the earth burn after they gave him so much trouble, that shows right there he enjoyed all the destruction. There isn’t any backstory on Thanos in the MCU to show how he got to where he was in life, so we can only speculate about it.
In the comics, Thanos was truly a madman that worshipped death, but he didn’t start off that way. He was born as a genetic mutation to the Eternal A’lars (father) and Sui -San (mother) on the largest moon of Saturn, called Titan. In the comics the Eternals are not the same as the MCU version…but that backstory is for a different article. For now, just know that they live an extremely long time (if they are not killed).
When Thanos was born, A’lars loved him on sight, Sui-San however, tried to kill him with a scalpel because of his mutation. A’Lars saved him and has Sui-San sedated. She later ended up in a mental ward. As a child, Thanos was extremely smart and a bit of a loner. He knew he looked different and he didn’t try to mingle much. One day some other kids asked him to play and he finally started making friends.
A’lars was the leader on Titan, and also the head scientist. He is also is the one that built the city of the Eternals on Titan and has been exploring the cosmos scientifically for 5 thousand years. Child Thanos only wanted to be a scientist like his father. He was such a pacifist that he actually threw up the first time he had to dissect a lizard in science class (all dissection specimens died of natural causes). There was no violence on Titan, Thanos didn’t know violence until a mysterious girl, who later turned out to be Lady Death in disguise, told him about a cave that was supposed to have amazing crystals in it. Thanos brought some of his friends to the cave to show them the crystals, then they were all trapped in a cave-in. Thanos was constantly being visited by lizards while he was digging out, but they never tried to harm him. He finally got out from under the rubble, only to find that all of his friends had been killed and eaten by the lizards.
At that time, no one suspected Thanos at all. It was just shocking to everyone that such a tragedy had even happened. Much later, after Thanos had built up a reputation for murder, the people of Titan would think that he had killed his friends. Lady Death is the one that pushed Thanos into his first killing spree. She told him that the feelings he had towards the lizards for killing his friends was natural and right. Thanos didn’t want to be a violent person at that time, he was feeling natural anger and rage because his friends had been killed. He was also alone, given that his father was always too busy to spend time with him. Lady Death took advantage of the situation by pretending to be Thanos’s friend so she could influence his development. Given that she is the embodiment of death, she probably had abilities that allowed her to see the potential power Thanos had, and maybe even different timelines his life could go on. She molded him into a person that enjoyed killing because she wanted more death. Given Thanos’s intellect and potential power, he could have been just as much a force for good and life if he had the right guidance, which Lady Death would most certainly not want.
The massacre of the lizards started Thanos down a path of violence that was heavily encouraged by Lady Death. As he grew older and smarter, he became very unsatisfied with school because it had very little to teach him. He craved knowledge, and with Lady Death twisting his thoughts, he started looking for answers in horrible places. He began capturing and dissecting animals….while they were still alive. He rationalized his bloodthirstiness by telling himself it was for knowledge, that he was a scientist. In reality, he was losing his grip on sanity, most likely due to not having anyone but Lady Death to direct his massive intellect. If his father had included Thanos in on his experiments and studies, most likely things would have been much different. Thanos had explored his entire moon, walked on the burning core of Saturn, and mapped stars from a thousand galaxies by the time he was 15 years old. He was a bored, frustrated, genius child, which is always a recipe for potential massive disaster.
When Thanos could not find his answers in the pain and suffering of the animals. Lady Death whispered to him that he was looking in the wrong place. At first, he thought she meant that she wanted to be with him. But when he tried to hold her, she rejected him, which made him even more angry and frustrated. When he expressed that there was nowhere else for him to look for answers, she told him he had not even begun looking. That is what started him down the path of killing people, which he is now so infamous for, and his lifelong obsession with pleasing Lady Death.
Thanos abducted and dissected two of his classmates. In the centuries before his birth, there had never been a murder on Titan. People could not even conceive of it. Nobody could figure out where the children had gone. Thanos’s grandfather, Kronos, was the only one that was thinking of foul play. He tried to convince A’lars that the children had been abducted, but A’lars would not listen. A’lars basically thought Kronos was being paranoid because of a war he had been in.
Thanos tried to tell himself, and Lady Death, that he is done killing. He tried to convince himself he was only doing it for science and that he did not enjoy it. Then, 2 weeks later, he was burying bodies again. He seemed ashamed when he admitted to Lady Death that he enjoyed it. Then she told him that there is no shame in being what he was born to be. She asked him to run away with her, then when he tried to hold her she slapped him and told him he was too weak to be worthy of her love. She messed with his emotions to keep him unstable. She even told him that killing is his only love.
Now he truly believed he was a monster and that the only time he didn’t feel alone was when he was killing people. He abducted his own mother (who was home from the psych ward) and then dissected her alive while telling himself he was looking for the answers to why he was the way he was. He thought he could cut the answer out of his mother, then he could stop being a monster. He never realized that the reason he turned into a monster was because of the mysterious girl that was actually Lady Death. After he was done killing his mother, he was talking to her corpse, telling her about his earliest memory of when she tried to kill him when he was born. He said he was sorry they wouldn’t let her do it.
The day he killed his mother, Thanos left Titan. He traveled to the far edge of the galaxy where he wouldn’t be noticed. He actually found a wife and had a child with her. Then he left and became a pirate. He refused to kill anyone like the rest of the crew, he used his massive intellect to help them track down and rob ships. The captain of the crew was not happy that Thanos would not kill people, and accused him of being a coward.
Thanos continued on the pirate ship and also continued to marry random females and have children because he was still looking for love. All of it felt empty to him. He lost track of all the women he married, the children he made and left, and all the people he saw killed. He didn’t really care about any of it. He was still in love with Lady Death, although he tried to forget about her. The women kept falling for him, but he did not have feelings for any of them.
The captain of the pirate ship continued to harass him and call him a coward for not participating in the slaughter that happened every time they boarded a ship. A fellow pirate warned him that the captain would kill him on their next trip if he didn’t leave. Sure enough, he was right. The captain attacked Thanos, and Thanos just taunted him instead of fighting back. The captain shoved his sword right through Thanos’s midsection, and Thanos continued to taunt him. The captain raised his sword to take Thanos’s head… Thanos closed his eyes expecting to die… and when he opened them he found himself standing over the body of the captain with all the crew hailing him as the new captain. To directly quote from the comic Thanos Rising “He opened them later to find he was not dead. Instead, he had just been born.”
From that moment on, Thanos began his reign of terror over the universe. He returned to Titan to visit his mother’s grave, and to find Lady Death. He never lost his obsession for her. She told him that if she was going to be with him, she would need to know that he belong only to her….
Thus began Thanos’s slaughter of all of his wives and children. He betrayed and murdered every last one of them so he could be with Lady Death. But even that was not enough for her. He continued killing as a pirate, and every time he asked her if it was enough, it wasn’t. One of the inhabitants of a world he was razing asked him why. Thanos told him it was nothing personal, he chose the world at random, and that he did it for love. Thanos told him to go into the ship and tell her what Thanos has done to his world, to his family, and ask her if it is enough. But when he went into the ship, all he found was a mutilated body of a female. When Thanos asked him what she had said, he made the mistake of first saying that she said nothing. Before he could say she said nothing because she was dead, Thanos blasted him and said “Then it is not enough”.
Back on Titan, Kronos was trying to tell A’lars that he needed to go stop his butcher of a son. A’lars still refused to believe that Thanos had killed his mother and was doing all the terrible things they had been hearing about. Kronos warned him that at some point Thanos would be returning to his home world. He said if A’lars didn’t do something, he would. A’lars simply stated that he is doing something, he is asking Kronos to leave…
Back on the ship, Thanos asked Lady Death when it would be enough. He wanted her to give him a number of people he must kill for her to be his. She told him that it will not be enough until he gets to the point where he stops asking that question and becomes the god she knows he is. He told her he already is. Her response was to accuse him of being afraid of himself…or the world where he was born….
Thanos yelled for the guards to come lock Lady Death up. They were terrified because they had no idea what he was talking about. Lady Death then revealed that Thanos is the only one that can see her. He didn’t believe her at first until she told him to say her name. They had been friends since childhood, but he did not even know her name. Thanos struggled to figure out her name…then she revealed that she is Death, “The only thing you’ve ever loved. The only being in all creation who could possibly love you back”. Thanos was shocked and horrified. He attempted to blast her through the head, but of course, that didn’t destroy her. Thanos rampaged through the ship, slaughtering his own crew until he made it to the combustion chamber. He stood on the edge of the platform, contemplating suicide until he realized that even after all the people he had killed, including his own mother, the one person he could not kill was himself.
Once he realized he could not kill himself, he went back to Lady Death feeling broken. He accused her of making him a monster. She told him that he was already a monster and that she just helped him along, she used his mother trying to kill him at birth to back up her claim. She said she would love him no matter who has to die and indicated that she would do it if he erased all of his ties to his past. At this point, Thanos was completely defeated emotionally and accepted her offer because he still craved her love. The residents of Titan never saw it coming…
After bombing the surface of Titan with everything he had, Thanos went down personally. The only one he allowed to accompany him was Lady Death. He walked the surface of the moon, murdering everyone that survived the bombing. Just when he thought he was finished, Lady Death pointed out that there was one more person left. Thanos’s father A’lars was still alive, and he had made a weapon. It took Thanos killing everyone on Titan before he finally accepted that his son was a monster. He had made the weapon specifically to kill Thanos… but he still could not pull the trigger. Thanos did it for him, just to see if the gun would work. It had no effect on the mad Titan. His powers had evolved past being able to be harmed by such a weapon. He then used those powers to blast his father into his lab.
Thanos decided that his father’s lab was a fitting place for him to be married to Lady Death with his father as a witness, given how many times his father had ignored him in that lab. A’lars realized that his son was in love with death and believed he could see her. He used the machinery in his lab to scan the room on every wavelength he knew of, to show Thanos that death was just his imagination and not really there. But even A’lars, with all of his thousands of years of exploration and research, could not grasp that not everything is definable by science. Thanos told him that Lady Death hides herself from all eyes but his, but A’lars was so convinced that his science and machinery would have been able to detect her if she was there, that he just assumed Thanos was crazy and imagining Lady Death.
There was a battle within Thanos between A’lars logic and science, and Lady Death telling him she is real, and that if he kills his father she will be his forever. Thanos left his father to live and told him he curses him with life so he can watch his son defile the cosmos. Then he left, feeling like he was completely alone and questioning again whether he was a madman. Lady Death kissed him for the first time, and he began his new reign of death and destruction.
Now in the present day, Thanos visits Titan once every solar cycle. He goes there to remember he was once an innocent, and that despite death being his constant companion, he feels he is always alone.
He still serves Lady Death. As we see in the Infinity Saga comics, he wanted to kill half the universe because Lady Death thought it was not right that there are more people living than had ever died. He killed all those people to please her. That is all he really cares about. “We Are Comics”