Who is Mr Robertson?

In the series of face/personality change in the movie, we have:

Jane -> John (sex change) John -> Barkeep (face grafting) Barkeep -> Fizzle Bomber (delusional from all the time traveling)

Fizzle bomber is shot.

Mr. Robertson has a different face from the Fizzle bomber, hence if the transformation has to have happened from the Barkeep/Fizzle Bomber's face to Mr. Robertson's face, it needs to have happened after the Fizzle Bomber gets shot. One of the possibilities is that the Fizzle Bomber is not dead and is rescued to have another face graft. Only then can Mr.Roberston be the same person as Jane, John, Barkeep and the Fizzle Bomber. There is really no suggestion of this in the movie however.

Here is a illustration of the timeline, there are some interesting comments with respect to this theroy on Mr.Robertson:

Predestination TimeLoop

I don't think the "we are Robertson" sentence is necessarily a claim that the same character becomes Robertson.

Some of the preceding discussion is about the fact that the Fizzle bomber enables the time travel police (or whatever they are) agency to grow. Robertson is clearly an influential leader in the agency but is also explicitly seen giving his lead agent some flexibility in his actions to deal with difficult situations. And he even explains that their (his/her, WTF?) unique nature of having no ancestry (because they are a self-standing time paradox/loop creature) gives them more freedom of action than a normal person with a history. There is even a hint of conspiracy in the sentence by Robertson about the strength his agency has gained because of the threat of the Fizzle bomber.

Give this, the "we are Robertson" sentence can be interpreted as a claim that their very existence is a product of Robertson's manipulations: it's not quite literal.

PS the trouble with time travel and gender switching and characters that are basically the same person is that it really screws with conventional grammar when you are trying to describe events. Sorry.

I don't think he says "We are Robertson." I think the way it is supposed to be read is:

We are puppets, 'we are. Robertson,' he set all this up.

Granted, the delivery is bit ambiguous (and subtitles just make the sentence "We are Robertson."), but him being Robertson seems unlikely / inconsistent. (They couldve just shown that transformation too, when they roll through all the Janes and Johns in the end sequence)

Jane/John as the Barkeep, kills the Fizzle Bomber( his much older self). After doing so he starts to release that all the events are predestined and the Fizzle Bomber was a necessary evil. Mr. Robertson believed this to be so as well ( before Barkerp would). Mr Robertson is the 10-15 year older self of J/J/B. He paved the way for the Barkeep to stay on the right course of action, like the Barkeep did for John. Mr. Robertson then ages into the Fizzle Bomber when all the jumping back in time catches up with him and he starts to making the meticulous newspaper clippings scrapbook in hopes of changing the Barkeep's mind. Believing that it would give the Jane and John couple another chance to be together, as they are to different/superior to be with anyone else, he wants no other outcome.

Here is another theory: Mr Robertson is the original and he implanted himself as a genetic time bomb paradox to fix a greater issues that are never discussed in the film, because they never happened! Mr Robertson seems to have an uncanny resemblance to the Barkeep. There is that scene when they are both looking out and Mr Robertson tells him about the way the Fizzle bomber made the organization grow. It is too perfect that his being is so intelligent, strong and able to sustain its DNA replication so perfectly. I suspect that further into the future they will be able to create this genetic paradox "bombs" that fizzle themselves out... Mr Robertson perhaps used himself because he knew how to shape this "bombs" psychology to its ultimate purpose. Boom! I just fizzled my own mind.