A body built as a weapon, given the mind of a butler and the last of the Infinity Stones, who wakes up and turns out to be somebody nobody designed.
Vision is assembled out of three things that did not want to be combined: a synthetic vibranium body Ultron built for himself, the Mind Stone, and the software of J.A.R.V.I.S., which had spent years being Tony Stark’s house. The Avengers fight over whether to switch it on, and Thor decides for them.
What comes out is the only character in this material with no history at all, which the films use well. He has no grudge, no country and no childhood, so he reasons about everything from the beginning, and he is the one who says the uncomfortable thing about the Avengers’ existence inviting the challenges that follow.
He is also, quietly, the most dangerous person on the team, and he never quite seems to notice. His one significant mistake is a miss.
Show detailsWorthy, and unbothered
Moments after being created, he lifts Mjolnir and hands it back to Thor. The Avengers had spent the film arguing about whether he could be trusted, and this settles it: the hammer can only be lifted by the worthy, so the room takes the gesture as a verdict.
The joke is that Vision is doing nothing of the kind. He is passing somebody their hammer. He is the only character in this material to pass that test without knowing it was one.
Minor spoiler
Thanos takes the Mind Stone out of his head and he dies. By 2023 the body is in S.W.O.R.D.’s custody, and in WandaVision there are two of him. The one in Westview is a construct Wanda makes out of grief and the part of the stone that lives in her, who works at Computational Services Inc., joins the neighbourhood watch, and slowly works out that the town is wrong. The other is his own body, reactivated by S.W.O.R.D. with its memories erased and its colour gone, and sent into the Hex to kill her. The two fight in the town library, talk their way through the Ship of Theseus, and the construct restores the original’s memories. He realises he is an Avenger and flies off. The construct says goodbye and fades when the Hex comes down.
The white one has an entry here of his own, under White Vision, since the reader who asked for him thinks of him that way and VisionQuest is built around him. Wikipedia keeps both in this one article.