Avengers: Age of Ultron feels so far away now. Pietro Maximoff is no more, Wanda Maximoff has become an irrefutable anti-hero who settled down with her fake family in a fake town, and the Avengers have since gained and lost several members, namely one of its earliest contributors, Iron Man, who sacrificed himself in the battle for the Infinity Stones to undo Thanos’ snap and restore half the world’s population.
From the earlier days of the MCU, when Wanda and Pietro were nothing but puppets in Ultron’s master plan for world domination, Iron Man’s user interface computer system — J.A.R.V.I.S. — was compromised by Ultron’s virus. In the end, J.A.R.V.I.S. is transferred into Ultron’s synthetic body, becoming henceforth known as Vision.
As for Tony’s replacement AI, he chooses F.R.I.D.A.Y., an interface patterned after an Irishwoman as opposed to an Englishman. She acted as Tony’s primary AI until his eventual death in Avengers: Endgame. When choosing his replacement AI, however, Tony skips over one of several databases, labeled “TADASHI.”
There was never any confirmation given as to what T.A.D.A.S.H.I. stood for, and we haven’t seen the U.I. chip since. While Tony’s acronyms are known to be whimsical and fun, Redditors seem in unanimous agreement that the name refers to the deceased brother of Hiro, the protagonist of Disney’s Big Hero 6, which is also a Marvel property.
In the movie, Tadashi — the creator of Baymax — rushes into a burning building to save Professor Callaghan of the San Fransokyo Institute of Technology. When inside, the building explodes, killing both Tadashi and Callaghan. As no official acronym was ever given to the ‘TADASHI’ U.I. chip, we can assume it was Marvel’s nod to a dearly departed animated character.
