Bruce Banner says in Avengers: Infinity War that Vision is composed of many layers when discussing how to destroy the Mind Stone. In those layers he includes himself.
Your mind is made of a complex construct of overlays. Jarvis, Ultron, Tony, me, the stone. All of them mixed together.
Is this some kind of metaphor or is there something else going on?
Maybe something happened between Avengers: Age of Ultron and Thor: Ragnarok?