- "Neil" is the last four letters of "Maximilien" read backwards. Max is the beginning, a boy who will go forward to become a friend of the Protagonist in the war against the enemies from the future, and eventually take the identity of Neil, a man who will ultimately go backward and find his end in the past.
- Maximilien is not a real name.
- It is a real given name. It's a French name, its equivalent in English is "Maximilian".
- Max lives in England; his mother is English and his father Russian. If this theory rests on his having a French name, it might be a little tenuous.
- He might have a French spelling of a name. It's a variant spelling of a very conventional English name. That's not an unusual thing at all. Many girls in English-speaking countries are named Emilie instead of Emily. What's tenuous about Max's full name being Maximilien instead of Maximilian? It's off by one letter.
- Once Kat is in his and the Protagonist's protection, he is the one to take care of her and treat her wound, and is implied to have spent a lot of time with her while inverted, prepping for the mission—maybe because he's a Nice Guy, maybe also out of affection for his mother, whom he'll never see in his own timeline again.
- In which case, Sator engineered his own downfall by forcing Kat into marriage and conceiving him.
- "Neil" is the last four letters of "Maximilien" read backwards. Max is the beginning, a boy who will go forward to become a friend of the Protagonist in the war against the enemies from the future, and eventually take the identity of Neil, a man who will ultimately go backward and find his end in the past.
Those FDBs are combated by the other FDBs who assisted Cooper. This second group of FDBs believe that they have no right to change the past and must own up for their mistakes. They made their own bed and now they must lie in it, so they decided to move on to other worlds and start over instead of trying to fix what won't be. This group is the one who made the events of Interstellar happen while also being the future incarnations of Tenet who seeks to ensure their opponent does not succeed in wiping the slate clean by influencing The Protagonist to start this faction in the first place. Think of it as a millennium-spanning Xanatos Speed Chess between two groups of FDBs in the far future. One wanting to erase everything and restart humanity over as they see fit, while the other wants humanity to own up for their mistakes in their own way without forcibly wiping out the past.
There's no indication that inversion was necessarily invented either by Tenet or by Sator's mysterious backers. It may have been invented by someone else and used by multiple individuals or groups in the future to send objects or people back to influence the past. Maybe someone decided to alter the course of technological development by, say, sending back some information to Nikola Tesla in the late 19th century? And Tesla used this information to invent technologies he never would have in our world, and over time this process of secret technological development led to Wayne Tech developing the memory cloth or extraction being developed by the government or whoever Cobb and his wife originally worked for.
Maybe this was done to create a process of technological development that ultimately makes inversion itself possible, leading to a Stable Time Loop.
The one or two men who broke into Leonard's house injured him. While he was in the hospital, the machine was used on him. However, it didn't quite work properly, and Leonard now exists in in a strange confusion of forward and backward. As a result, the movie memento was not just representing how Leonard thinks, it represents how time actually flows for him. However, the incomplete inversion process means Leonard skips backwards in time, with forward segments to connect, rather than continuous backward time travel. The inversion failure also goofed up his memory somewhat.
The protagonist must have spent years and tons of effort to build up such a powerful organization, right? Not necessarily.
- To recruit agents: In the protagonist and Neil's case, both kind of recruited each other. Neil taught the protagonist some important details, and protag did so whenever he recruited Neil. Some inversion happened at some point to generate a closed loop. If tenet agents take part in similar cycles, while making sure to hire some extra agents, than the whole organization could recruit itself.
- Tenet's philosophy/way of operating is a similar time loop: the agents teach the recruits, who tech the previous recruits, and everything cycles around.
- By using inversion, tenet could use its resources to acquire resources in the past (like the ships, guns, containers, etc.), which are than used to buy things in the future. Tricks like taking advantage of the stock market or future business knowledge could generate money.
- Priya said "Tenet wasn't founded in the past" which would technically be true, Tenet would not have been founded at any particular time. Saying that "It will be founded in the future" is a misunderstanding.
Inverted and normal objects are said to annihilate if the make contact. However, this is impossible, to touch its time reversed self, an object would have to touch itself, continue existing, get turnstiled, than touch the original, but by touching itself it was annihilated, so it can't go back. There's also no physical reason for this, skin constantly sheds, food is eaten, material corrodes, etc., so the exact particles are never the same.
The source of this story is instead a turnstile accident. When designing turnstiles, someone at some point didn't move the inverting objects, instead inverting in place. Doing this places 2 copies of each particle in the object at the exact same place at the exact same time at the instant of inversion, which is impossible, so the object exploded. Turnstiles are always designed to move as a result. When the people involved explained this to others, the story was distorted and simplified into "inverted and normal objects that touch themselves annihilate".
- Basically confirmed in-film by the fight scene the Protaganist has against himself
- OOOHH!! This is now head canon for me!
He obviously absorbed a bit in the car chase, but the fight with himself, experiencing the same event from both direction, really taught him how to think with inverted time and understand how people act. After the fight is when he actively helps plan the event with Priya and helps organize the final battle.
It is almost certainly in the movie to help us the audience in the same way.
Bam. Physicists, where's my nobel prize?
