This, by the way, is the universe in which Wade did not tell the Avengers he was returning Darcy to them. That he still returned her to them is worthy of consideration, but the reasons why he did so remain a matter of speculation.
That he did is all that matters.
That and the explosion.
Did I forget to mention the explosion?
It began with the Lizard trying to take a bite out of Colossus' attractive metal ankles while Wade, James and Clint attempted to escort Darcy back to the tower. While James and Clint had worked out Darcy's location on their own, uncertainty had left them failing to notify the other Avengers that they might need backup. So when the tetrad became surrounded by enemies on the mean streets of New York City, Wade reacted appropriately (for once) to Darcy's need to have all of her beloveds safe and teleported them to the Avengers tower. (The other alternative involved murder poodles. The world is grateful.)
And where did the teleporter take them? To the location where his flowers had shown up some days before, the site of Dr. Jane Foster's lab.
Not, perhaps, the wisest of locations to choose as a teleportation destination.
At the time, Dr. Foster, being without adequate supervision, was in the middle of a breakthrough. That this breakthrough occurred after 36 hours without sleep is both unfortunate and relevant. At the time of the breakthrough, both Thor and Tony Stark were present in the laboratory space, Tony drawn there by the pulsing waves of force emanating from the work space and Thor in hopes of coaxing his lady love to rest.
Thor, let it be said, while an excellent warrior, was not well-suited for battles of words or wills with women.
At the time Wade and his three passengers teleported in, striations of color had begun to accompany a high pitched whining noise.
"I am certain that this is not normal," Thor said, approximately twenty seconds earlier, clutching Mjolnir like a baby with a pacifier.
"I'm certain that it's *amazing*!" Tony replied. "Jarvis, you're recording this, right?"
"Yes, sir. But perhaps this would be a good time to retreat to a safe distance?"
It would, indeed, have been a good time to retreat to a safe distance because, at the same moment, elsewhere in the universe, another event was also occurring, equally important although unwitnessed by anyone.
In the stasis chamber constructed specifically for the purposes of keeping him alive as long as possible, Odin was taking his final breaths.
No one knew of this, for another Odin sat upon the golden throne. As the throne allowed its occupant to observe whatever they wished, the imposter could have kept track of Odin's every breath. But the false Odin had far too much on his mind, being frantically occupied with the monumental task of stalling Thanos in the titan's goal of invading and conquering the nine realms. Successfully, mind you.
Had he been paying attention… but alas, he was not.
Thus all things happened as they ought, creating the perfect storm of events.
The machine malfunctioning in Dr. Foster's laboratory held open a small portion of the Bifrost -- not enough for transport, just enough to tap into and meddle with. Wade and his three passengers landed on Thor's back, sending him sprawling into the machine, making direct contact between it and Mjolnir -- the artifact forged in the heart of a dying star -- at the exact moment that Odin died and the Odinforce left him and possessed his son instead.
If all of these things had not happened as they did, the resulting event would not have taken place. But they did and it did.
A rainbow arced out from the point of contact between Mjolnir and the machine, encompassing it and expanding outward in a visible wave some twenty stories tall. It caught most of the tower in its grasp. But its effects stretched far beyond the visible.
And when it passed, the universe had become a little more strange.