Avengers: Infinity War - 11 Things That Definitely Won't Happen
11. Thanos Courts Death
In order to become a villain worthy of the hype, Thanos needs a powerful motivation for collecting all the Infinity Stones and destroying half the universe.
In Infinity Gauntlet, the reason he does this is to court Death herself. A cosmic entity and the physical embodiment of death, Lady Death at first doesn't see Thanos as an equal and, even after he's assembled all the Gems on the Gauntlet she continues to reject him, leading him to wipe out half of the universe.
This was hinted at in Thanos' first appearance, during the post-credits scene of The Avengers, when he turns and smirks at the words "court death". Somewhere along the way, however, Marvel decided to would be a bit much to have literal Death involved in the movie, and even the notion of having Hela fill that role (as once rumoured) won't be happeing.
Thanos is instead motivated by the destruction of his home planet Titan, and now he sees the same thing happening elsewhere - what he views as the universe being ruined and imbalanced - so he's destroying half of it to save the rest.