One of the most surprising things about Avengers: Infinity War was that it made Thanos, who up to this point in the MCU had just been a very angry purple man, into a complex character with pathos, a tragic backstory and, oddly given his mission to wipe out half the sentient life in the universe, a soul.
In the film, his motivations for those goals are watching his home planet fall into ruin over a battle for resources, which made him realize the universe will inevitably head the same way unless someone does something about it. But in the comics, the Mad Titan had a slightly different motivation. He really, really wanted to bone the Marvel Universe’s Death, who’s a cute girl in a hooded robe playing very hard to get.
Given that Death just hangs around him staring blankly in his direction, Thanos figures the best way to get
senpai her to notice him is to kill so many people that she can’t help but fall for his purple charms. Also, in a great twist, only he can actually see Death, so a lot of the time he looks straight up crazy pleading with an invisible woman to fall in love with him.
Though the Russo brothers considered working some aspect of this into Infinity War, they decided that audiences have enough to process without tossing in personifications of innate cosmic forces. But now, fans are speculating that the character might appear in Avengers 4 – with newly-dead Gamora taking up the mantle of Mistress Death. The theory is borne from the scene immediately after the ‘Snappening,’ in which Thanos appears in a world with an orange color scheme with a young Gamora in the centre, perhaps symbolizing that her soul remains locked in the stone.
Personally, I think it’s a bit unlikely that the green-skinned Guardian will take on the Mistress Death role and plus, it’d be a little bit gross if Thanos’ adopted daughter was reincarnated as his lover – and might stretch the believability of the MCU too far. Still, all my Infinity War predictions were off way base, so don’t pay much attention to what I think about Avengers 4.