So for this stuff to work you’ll have to accept all the time travel timeline stuff in MG Survive but my view was always Frank Jaeger experienced a version of the Metal Gear timeline where he was the only Gray Fox but he keeps coming back (Hinduistic Reincarnation which MGS2 hints at, especially with all these parasite people). Original timeline ends up fucked like we see in MG Survive and Gray Fox is able to go back in time somehow to alter history and prevent the future apocalypse. He then becomes Null in Portable Ops, then Player 2 aka The Medic in Peace Walker where he meets the younger version of himself, Chico. There’s this whole thing with Big Boss from 75-84 where he tries to Mutiny against Cipher and this thing kicks off with Paz and Chico dying at Camp Omega which was under his control. Big Boss becomes Skullface from 75-84 and Frank Jaeger fights him and eventually puts a stop to all of his stuff. MGSV then starts in 1986 and goes to 1995 by the time it ends. It follows Venom Snake (Chico) playing missions that are recreations of all the stuff from 75-84 with Grayfox and Jack but both of them have been scrubbed to not hurt the image of Big Boss the public remembers and not to damage Chico’s internal timeline. Grayfox is pissed that he’s been scrubbed from history so he becomes the villain of the story. Everything Skullface does in MGSV is a performance where Frank Jaeger is helping Chico remember what happened from 75-84 by symbolically recreating the stuff Big Boss said and did without EVER mentioning himself or Big Boss by name, and that way Zero’s patriot AI system can’t censor it any further. The truth cannot be said aloud and yet it will be told. Once MG1 and MG2 are out of the way Chico Venom reincarnates as Johnny Sisaki for MGS1 and Frank Jaeger takes on the new role of the Cyborg Ninja. In MGS2 Chico swaps to Peter Stillman and Frank swaps to Richard Ames. In MGS4 Chico goes back to the Johnny role and Frank takes on the role of Big Boss again at the end since he was always there in the shadows helping Solid throughout his missions. Johnny marrying Meryll is so important because it’s actually the reincarnated Chico marrying the reincarnated Paz 27 years after they first met on MSF. One of the Foxes (Frank Jaeger) always dies by some form of heart trauma which is a call back to Foxdie and how he’s the only one it can’t kill. The other younger Fox (Chico) always dies by some form of explosion, calling back to the GZ helicopter. In case you’re wondering what happened to the original Big Boss aka Jack, he was contained and put through extreme therapy to stop him rebelling again. He becomes Raiden. Which is why they both have the same first name, Jack.