Doctor Strange, Stephen Strange, the Sorcerer Supreme of Earth, the undisputed master of magic in the Marvel Earth. He's often nicknamed the "Kidney-Deficient Sorcerer" because, despite being a canonically maxed-out character in Marvel with all stats at 7 (the highest being 7) and having an overpowered mechanic, he inexplicably flops and becomes a stepping stone for enemies whenever something big happens, much like the Flash, who gets banned daily.
But that's not important. What's important is that it's now September 2012, and something has happened that seems to have advanced Doctor Strange's timeline.
"Excuse me, who are you?"
"Strange, you can call me Doctor Strange. I am the Sorcerer Supreme of Earth. My responsibility is to protect our reality from any supernatural invasions and destructions, primarily those of a magical and rule-based nature." Strange briefly introduced himself. Peter suddenly thought of something and couldn't help but chuckle: "Sorry, is Strange your... name or a codename?"
"My surname is Strange, thank you."
Seeing Strange's gaze gradually turn cold, Peter also suppressed his smile: "Sorry, um, I actually mostly understand what you mean. A woman named Madame Web told me about the Web of Destiny and totems. This is my ability; I know what I'm doing."
You know nothing!
Strange's gaze grew colder as he floated before Peter: "Do you know how many spells I just cast to prevent our universe from emitting abnormal vibrational frequencies? I know your soul is protected by the Spider Totem, and you are the Great Weaver. It's your responsibility to travel through the multiverse to save your totems, but that doesn't mean you can act so impulsively."
"You mean my actions are like using a door to pinch someone's foot? A door should be for entering and exiting, not for pinching feet."
"Yes." Strange, momentarily caught in Peter's seemingly logical description, immediately reacted, then exclaimed, "No! My goodness, listen, that's not how things work."
So, under Doctor Strange's little magic knowledge-sharing session, Peter finally understood some basic knowledge about this multiverse.
In this Marvel multiverse, every jump between universes is itself a tear in the fabric of reality. The difference is that some tears can be repaired, like the multiversal travel machine Mister Fantastic will build using Peter's multiversal travel data in the future, while others are irreparable. There are also some special cases, such as using entities like the Web of Destiny, which inherently transcend the scope of the multiverse and have no effect on the fabric of reality itself.
This is also why the 616 universe's reality barrier is incredibly thick, yet Peter can still cross it.
But even so, any multiversal travel will cause a vibration in both the originating and target universes. This leaves a trace, and if a civilization or individual can detect this trace, they can determine which universes have multiversal travel capabilities.
"And what you're doing is telling the entire multiverse that you have the ability to travel through the multiverse, that you're a human multiversal travel machine," Strange said exasperatedly, looking at Peter. "What if someone discovers this and catches you the next time you cross over? Hmm? You might become a tool for others to invade the multiverse. Nothing's impossible, kid. Even if you stubbornly kill yourself, someone could still use your corpse to continue all this."
"Uh, alright, so...?"
"So I'll be watching you and cast a spell on you. This will make it harder for you to tear open spatial rifts. It'll make you think about whether it's really necessary. And once you do tear open a spatial rift, I'll observe whether it was necessary. If you, like today, just haphazardly open a spatial rift just to take down a hooligan—"
Strange shook his head, gravely warning Peter.
"I'll turn you into a human spider and throw you into the Sahara Desert."
Well, that was certainly a serious warning.
Peter, unfazed, quickly nodded. He probably understood the dangers of frequently using his abilities. As Strange began chanting a spell and casting it on him, Peter also chatted casually: "May I ask how old you were when you became a sorcerer?"
"Two years ago. I only became Sorcerer Supreme a year ago. If a certain little brat hadn't been born three years early, I probably would have become Sorcerer Supreme three years from now."
Strange glanced at Peter as he cast the spell. He wasn't blaming Peter; after all, Peter probably didn't even know why his destiny had been altered, leading to his early birth. Strange quickly finished the spell and prepared to leave, but Peter still stopped him: "Uh, Doctor?"
"What is it, kid?"
"Aren't you going to join the Avengers?"
"I've made myself quite clear," Strange raised an eyebrow. "You protect the world, and I protect reality."
"And the world we protect has nothing that helps reality?"
Strange, seemingly unaware that he had been tricked into speaking, nodded: "Actually, there is one thing: that Asgardian Loki's scepter. It's currently the only Infinity Stone on Earth. If you can entrust it to me, Earth will be much safer."
"Only?!" Peter exclaimed, realizing his slip of the tongue, then quickly tried to recover: "You mean, there's more than one of these things?"
"Infinity Stones are special substances, each with a unique function. In the past, the Space Stone was hidden on Earth by Odin, which was the Cosmic Cube. Now the Cosmic Cube has been taken by the Asgardians, so only one remains."
In other words...
The Time Stone wasn't in Strange's hands. No, perhaps the Time Stone was never on Earth.
This was a huge problem. Although Strange had become Sorcerer Supreme, he had most likely dealt with Dormammu, but the absence of an Infinity Stone meant a complete collapse of the timeline. The MCU's story would be even less relevant as a reference for this universe.
"Then what if they're all gathered?"
Peter took a deep breath, calming himself. Strange, however, seemed to have truly only come to warn Peter. He left without even answering Peter's last question. Peter looked out at Manhattan, and for the first time, had an unrealistic feeling: the future was shrouded in a thick fog.
Would Infinity War really arrive in 2018, just like in the movie?