Fans of the Marvel Cinematic Universe have known since 2012’s The Avengers that Thanos is coming, but one important question still remains unanswered: “Why is Thanos coming?” Thanos has made his intention to collect the Infinity Stones perfectly clear, but it’s still not entirely apparent why he wants them so badly. However, readers of Marvel Comics may have a leg up when it comes to figuring out the motivations of the Mad Titan.
Thanos has a long history of trying to get his hands on the Infinity Stones in the pages of Marvel Comics. He’s even managed to do so on a couple of occasions. Although he’s been around since 1973, Thanos’s character and motivations have remained remarkably consistent: he wants to assemble the Infinity Gauntlet because it will help him kill more people, and Thanos loves Death. That’s not a metaphorical statement, either - Thanos is madly, deeply in love with the concept and personification of Death, and that’s what has driven him to become one of the greatest villains in Marvel history.
In the comic books, Thanos’s internal character motivation centers almost entirely around his peculiar romantic interests. Thanos is in love with Death, and not in a metaphorical sense. A personified version of Death exists in the Marvel Universe, and Thanos will do anything to win her affection.
Death alternates between appearing as a beautiful woman and a skeletal figure. While multiple Marvel characters have had interactions with her, only one of them has fallen head-over-heels in love with her - Thanos, the Mad Titan. Some villains chase money, others seek control, but Thanos just wants Lady Death to love him back.
Thanos’s infatuation with Death started when he was just a simple purple boy growing up on Titan, a moon of Saturn. After a couple of traumatic childhood incidents, Thanos began to see a mysterious girl everywhere he went.
Although it takes him a while to realize she is the personification of death, it doesn't take him nearly as long to start murdering in her name. Thanos racks up an impressive body count before he hits space-puberty, including his own mother. He eventually settles into a career as an intergalactic conqueror so he can further his genocidal endeavors.
Like many individuals on the wrong side of unrequited love, Thanos finds it necessary to constantly prove himself to Death, only to be largely ignored for his efforts. Thanos rarely receives any affection from Lady Death, but he’s convinced himself the key to her heart is wanton murder.
Thanos kills dozens on his own planet, but fails to impress her. He wipes out entire alien races and still gets the cold shoulder. Even when he returns to his home world and slaughters his own people, Death stifles a yawn.
Thanos’s quest to win Death’s love has ever-increasing stakes, and the poor guy doesn’t seem to realize she might just be stringing him along to serve her own fatal interests.
Thanos is born to a super-powered race called the Eternals, who left Earth and colonized Titan. He isn’t a typical specimen of the Eternal race, however. A rare mutation results in Thanos being born as a “Deviant” - cursed with a hideous appearance, but blessed with powers far stronger than the average Eternal.
Still, Thanos seeks more, and so he uses the scientific abilities he inherited from his father to augment his strength with various cybernetics. No matter how powerful he becomes, however, Thanos is never satisfied, and he continues to search for true omnipotence.