shatterfrytheplasmicshell answered your question “as someone who only very recently got a grasp on the complexity of the...”
I would assume that characters from the Netflix shows and the Agents of SHIELD won't be in it but I wish that at least the Defenders would be. And I really hope that Gaurdians of the Galaxy will be there but they might not.
My most recent wikipedia-ing has them confirming that at the very least Chris Pratt’s character from GOTG is definitely in it (along with Thanos obv). Then a quote from Krysten Ritter that she would love to have the Defenders characters involved, but they were quoting her purely on what she would love to happen and not what actually will likely happen? I hope they include the Defenders.
Of course you can’t believe everything you ready on wikipedia unless it has a source directly linked to it and that link works, and even then, there’s so much info for those two films alone and speculation about who will be in it that it was a lot to account for.
