It has been three months -- and one Spider-Man movie -- since Avengers: Endgame was released and diehard Marvel fans still have a laundry list of unanswered questions about the film: About the fates of Iron Man (Robert Downey Jr.) and Black Widow (Scarlett Johansson) and the whole is-it-a-multiverse-or-not debate, among many, many more.
Hence why there were still major revelations to be had during back-to-back San Diego Comic-Con panels on Friday: "Writing Avengers: Endgame" with screenwriters Christopher Markus and Stephen McFeely and "A Conversation With the Russo Brothers" with directors Joe and Anthony Russo. Below, here is everything we learned:
1. Avengers: Infinity War almost featured The Living Tribunal
Benedict Cumberbatch's Doctor Strange got to flex his sorcerer powers during Infinity War's battle on Titan, but a version of the sequence saw a more psychedelic take that would have also introduced a new comic character, The Living Tribunal.
"We stuck the Living Tribunal in the movie, who you may know is a gigantic guy with four faces on one head that rotates and passes judgment on you. As Thanos and Doctor Strange came to blows, Doctor Strange blew Thanos' mind and sent him through the mindscape," Markus said. "The idea was that he was sent through the universe confronting his many, many, many, many crimes...At the very end, he gets dumped in front of the Living Tribunal who judges him guilty."
"It was great," McFeely added. "But when you introduce the Living Tribunal it opens up another era-- I don't think my grandma would understand that." The scene would have taken place amid a high-octane fight sequence, too, and "to stop it to have an LSD trip was fun, but sucked the air out of the punching."
2. Professor Hulk was originally present when the Avengers kill Thanos
Bruce Banner (Mark Ruffalo) and Hulk merged in the third act of Infinity War, initially. "We wrote it. We shot it. He achieved union with The Hulk while inside the Hulkbuster," Markus explained of a scene set in Wakanda. "He burst out and kicked Cull Obsidian's space ass -- and it didn't work."
"It was completely the wrong turn for that moment in the movie," he continued of why it was ultimately adjusted. "It was a victory when we were heading for a crushing defeat. But we had already shot Endgame."
Which means that Smart Hulk was around in the first act of Endgame, including the sequence where the Avengers kill Thanos. "So, that required some adjusting," Markus said. So, the Russos moved the transformation to after the five-year time jump during reshoots.
"A big sequence where you see these two guys achieve union takes time and it takes attention away from the story," Markus added. But a scene where Smart Hulk lays it all out over pancakes? "It's fast, it's funny and it's a scene I haven't seen in a superhero movie before."
3. Natalie Portman could have had a larger role in Endgame
One of the unexpected surprises of Endgame was that Portman recorded new material as Jane Foster -- albeit, dialogue only. An early scene, however, saw Rocket (voiced by Bradley Cooper) attempt to explain the Time Heist to Jane instead of stealing the Aether. Jane, being a scientist, would have been really excited by the idea of the quantum realm.
"It was very satisfying," Markus said. "And cute," McFeely weighed in.
"But we had a three-some-hour movie," Markus explained. So, ultimately the scene had to be cut, allowing for more time to be spent on the emotional beats between Thor and his mother, Frigga (Rene Russo).
"We wrote a scene with him and Jane, but Jane isn't the person to put him together. Odin isn't the person to put him back together. Really, it is only his mom." Markus added of why the Jane and Rocket scene ultimately took place off-screen. "Plus, we never know how the Aether turns into a Stone."
4. One Endgame twist nearly included Captain America's decapitated head
With present-day Thanos beheaded, the writers knew they had to eventually bring Thanos from the past into the present. How that would ultimately come to pass could have been far, far more gruesome.
"In one, he, being Thanos and knowing it would take Nebula some time to rejigger the time machine and bring him back, he went down to his present-day Earth and wiped it out and killed the Avengers," Markus said. "Then Nebula would turn on the time machine and he would walk through with [Captain America's decapitated head] and go, 'I killed you, again.'"
"Giant Man's corpse was in the background," McFeely revealed, with Markus noting, "We were borrowing from Old Man Logan. It's a hell of a comic book."
In the polar opposite direction, another scenario saw all of the snapped Avengers blipped back to HQ -- the big reveal being Peter Parker (Tom Holland) popping around a corner saying, "Mr. Stark?" -- and five minutes later, they were having a pizza party.
5. The Endgame writers also thought about how Captain America would react to meeting Red Skull on Vormir
Endgame ends with Steve Rogers (Chris Evans) setting out to return all of the Stones to their rightful place in the timeline. But considering the events of Captain America: The First Avenger, how would Cap's returning the Soul Stone to the specter of Red Skull go, exactly?
"There's a fascinating one-act play to be written of Captain America going to Red Skull," Markus deadpanned. "Never wrote it. In the manifesto document [of all the potential ideas that could be explored in the movie], there was one theory that it's Cap who goes to space and he has to collaborate with Red Skull to get the Stone."
Another popular fan theory has claimed that when Steve returned the Soul Stone, he might be able to revive Natasha (Scarlett Johansson). Moderator Jeff Goldsmith (of "The Q&A with Jeff Goldsmith" podcast) joked that it would be like the reimbursement you get when you turn in recyclables. "Does he get his Natasha deposit back?" McFeely laughed. "Listen, that is not the intent. The intent is that it's a one-way street."
6. Here's what may have happened to Steve Rogers after Endgame
After Steve returned the Stones, we know he stayed in a past timeline with Peggy Carter (Hayley Atwell). During the Russo brothers' panel, they fielded "fan" questions from the likes of Chris Hemsworth and Paul Rudd. But it was Evans who had a particularly pressing inquiry.
"After Steve returned all the Infinity Stones and finally got his dance with Peggy, what was the next thing he made sure to do?" Evans asked.
"Perhaps he and Peggy tried to make a baby?" Anthony pondered.
"I think he went to the bathroom because it took him a long time to return those Stones. He'd been holding it for a while," Joe joked, before more earnestly weighing in: "If you think about it in terms of the alternate reality theory...Steve could do a lot of things: He could go rescue Bucky from HYDRA [or] he could go find himself in the ice and figure out a rotation where the two Steves could take turns and he could spend more time at home with Peggy."
Follow along all weekend on ET Live and check out ET's YouTube page for videos of all of our exclusive Comic-Con interviews.