SPOILERS FOR ALL OF TENET
I believe that Robert Pattinson and Elizabeth Debicki's son are the same person at different ages. Robert Pattinson's final words are "We've known each other a long time, but this is my end to our story, and your's is just beginning," which he says to John David Washington.
Robert Pattinson is Elizabeth Debicki's son from 25 years in the future, who has to go back in time to take a bullet for John David Washington in the tunnel to stop Kenneth Brannaugh's endgame, AND allow JDW to live to confront Priya before she kills Elizabeth Debicki and her son. If Robert Pattinson dies as a kid (by Priya), then he cannot help JDW stop Kenneth Branagh, and if JDW dies disarming Tenet, then he cannot stop Priya from killing Robert Pattinson as a kid.
If you want to hurt your brain a little more, I believe that there was a Star-Lord-smacking-Thanos moment of selfishness when Elizabeth Debicki kills Kenneth Brannaugh's character prematurely, forcing Robert Pattinson to improvise. You can see a building reverse explode from the top, then blow up from the bottom instead. Robert Pattison mentions changing arm band colors (red and blue), but I believe we saw TWO 25-year old Robert Pattinsons who both martyr themselves to ensure that ONLY their 5-year-old self survives. This is seemingly confirmed when we see JDW and RP run into the tunnel the SECOND TIME, as we follow RB who is driving a vehicle.
TL, DR: John David Washington (age 25, from now) meets Robert Pattinson (age 25, from future), they use Priya and her resources to stop Kenneth Branagh, Robert Pattinson (25, from future) dies protecting John David Washington, to ensure that John David Washington kills Priya, preventing her from killing Elizabeth Debicki's son, Robert Pattinson (age 5, from now).
Submitted August 28, 2020 at 04:40AM by SekiroMTL https://ift.tt/2QtrDST