In the last episode of Fringe, Peter finds a tape addressed to him, which was encased in amber. In this tape Walter says that if Peter is watching the tape, that means he probably got a weird letter from him and decided to go look for him the lab, thus finding such tape.
This tape was there since 2015, when Walter had already sent the letter and inoculated himself to go with Michael to the year 2167. But then something happened, and Walter had to amber the whole thing.
But this means that for the tape to have been recorded, the invasion must have taken place and Walter must have formulated his plan.

Fast forward to the end of the episode, once the timeline is reset, Peter gets said letter in 2015. However, unless I have misunderstood something, this is impossible.

From what I understand, the timeline goes something like this:

  1. Peter and Olivia in the park with Etta.
  2. Invasion of the Observers.
  3. Etta disappears.
  4. Walter elaborates a plan to prevent the invasion.
  5. Walter understands he will have to sacrifice himself and go with Michael to 2167.
  6. Walter records the tape and sends Peter the letter.
  7. Walter was going to the future, but instead encased it all in amber, and then stays like that for 20 years.
  8. All the events in Season 5 take place, ending with the timeline being reset.

Since resetting the timeline would modify things from point 2 onwards, how could Walter have sent Peter that letter? He could not have sent it (and recorded the tape) before the invasion took place.
Am I missing something or should we assume that the Walter in the future thought about this later and found someway to make the letter and the tape 'appear' in 2015 (in the reset timeline)?

  • 3
    keep in mind that September was working w/ Walter before the invasion actually happened, since he knew it was coming. I don't think the timeline is ever explicitly stated as to when the plan itself was finalized but parts of it definitely could have been in place before the invasion.
    – KutuluMike
    Jan 21, 2013 at 1:43

12 Answers 12


I almost asked this same question, but I think I figured it out while trying to form the question. All it requires is good timing on the part of Walter.

  • The plan was being put together from 2013 through 2015, if I recall correctly.
  • The invasion (and the scenes with Etta in the park) happened in 2015, which is also when Walter ambered the lab and the team.
  • September said that he didn't know what Walter did with the card, which implies he knew Walter had it while they were working on the plan before 2015.
  • In the reset timeline, the card appeared to arrive on the day in 2015 when the invasion would have happened.
  • Given Walter and Donald planning to exchange places, I'm not sure how accurate this is - but Walter said that the paradox that would erase him would occur at the time of the invasion in 2015.
  • I believe earlier on in the season (but can't recall for sure) that someone said the invasion happened just when they were ready to enact the plan.

The intended timeline - and what apparently happened after the reset - was this:

In 2015, all (or, almost all) the pieces of the plan were together, and all they had to do was implement it. Walter knew this, and mailed the letter to Peter. A day or two later, Walter had vanished and Peter received the letter (seen in the last scene) and would later find the video.

Unfortunately, the invasion interrupted the last parts of the plan. Walter had sent the letter already at this point, so it was simply lost in the in post in the chaos during the invasion (This would explain why Peter didn't know about it, and Donald didn't know what happened to it). In a panic, the team quickly tries to get together the pieces to implement the plan, leading to them all being ambered and the events of Season 5.

There's a bit of fuzziness in that the plan had not been implemented by the time the Observers appeared in the invasion, so the paradox should have erased Walter before it was implemented, but he doesn't appear to have been entirely truthful about that anyway, given he was willing to trade places with Donald. It seems more likely the paradox would have occurred at a later point during the invasion when the plan was implemented - which would seem to resolve the inconsistency.

  • 1
    Do we actually know how long between "the invasion happens" and "Walter ambers everyone"? There was a sizable gap, during which Peter ran off to look for Etta and Olivia didn't. I assumed it was many months, if not > 1 year but I dunno.
    – KutuluMike
    Jan 21, 2013 at 1:42
  • 1
    @MichaelEdenfield Season 5 takes place in 2036, and it's been mentioned a few times that they were trapped in amber for 21 years. So it's almost certainly not longer than a year, likely a couple months at most. However, prior to the invasion, the Observers know who Peter, Walter, Olivia, and Astrid are, so their homes weren't necessarily safe anymore. Invasion point onward, I don't think they could risk going back home for something as trivial as mail.
    – Izkata
    Jan 21, 2013 at 1:52
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    @Izkata Was it said in the series that the plan was being worked on since 2013? I really don't remember that.
    – JNat
    Jan 21, 2013 at 12:27
  • 1
    @JNat To be honest, I'm not certain when exactly they started working on it, but I'm pretty sure I did hear 2013 at some point. Either way, Season 4 finale: "They are coming."
    – Izkata
    Jan 21, 2013 at 13:29
  • 1
    @JNat I definitely think so. Olivia ambered herself while retrieving the Transilience Thought Unifier, which was needed so Walter could remember and enact the plan.
    – Izkata
    Jan 21, 2013 at 13:39

Walter is not entirely erased from the timeline. He ceases to exist FROM 2015 because he cannot exist in two places at one time. If you watch the tape that Walter left for Peter it answers all this. Walter knew Peter would remember him and not know where he had gone. He says you will find the letter, then call me, I wont answer so you will come to the lab to find me. Peter will then watch the tape and understand that Walter is now in the future. In the tape Walter says "I was here one moment then vanished from the face of the earth the next". So he was there. They knew him. He just ceases to exist from this point.


Timeline has been restored! The observers got Michael and clearly studied him! Michael is alive in the year 2167 since there's no invasion. So that means September is alive too in the future since he's michael's father but he himself was Born "updated" if u will! Meaning that the observers still happen( don't forget he saw all the different possibilities about different future) and September could've been the one that posted the letter to Peter in the end letting him know that Walter is sound and safe and to keep the faith! That's how I look at it anyway!


I really don’t mean to offend, and if I’m mistaken please correct me, but I think you guys are missing the point....Walter is erased from the timeline. I understand he did a lot to make possible all season 5 events, but the beauty of Michael is that he understands all timelines. The beauty of re-writing timelines is that everything is possible in infinite different ways... Walter is gone, but to make possible the events of now, other actions and things must have occurred.

So the issue is much deeper. That being said... He’s Walter Bishop. If Fringe has shown us anything it’s that some people make such an impact on ones soul that they can’t let them go. So the end scene. A close up of peter’s eyes whence seeing this white tulip. I wouldn’t put it past Walter to develop a way to make a letter impervious to timeline shifts. He’s Walter.

That’s my take on it.


There has to be an assumption that Walter knew about the invasion before it occurred, and set things in motion for the plan before the Observers arrived. The only way Walter could have known is if September/Donald told him.

And if that is the case, you might still wonder why Walter never told or warned Peter about the invasion that could occur if their plan goes south. Would he have not wanted to warn Peter about what might happen, especially as 2015 was closing in, and he was still not ready for the implementation of the plan?

And let us not forget that he did not have all the devices he needed at that point of time when the invasion occurred, which is the reason why he sent Olivia to go looking for one. And this was clearly after the invasion occurred. She was almost captured, but ambered herself. It makes sense that they merely just documented the plan, as the others say here, but they barely even began implementing it. It does not explain, however, why Walter would send a letter so prematurely, when he did not even have everything to go through with the plan yet in 2015...there is definitely some lack of foresight on the part of the writers here.

Another screw up is the idea of Peter and Olivia being together, after the timeline is reset. This is also "Impossible." If there are no observers, then there is no September. And if there is no September, Walternate would discover the cure for Peter himself (as he would not have been distracted by September), which would at the very least mean that Peter would never been removed by Walter from his birth-universe. That would mean Peter would have never met Olivia, as he would never have been in the prime universe. I think the writers merely focused on events starting at between 2013 and 2015, and neglected the effects on the earlier years. Essentially, they neglected the consequences of the absence of September.

  • Great answer, thanks!
    – JNat
    Aug 7, 2014 at 21:26
  • Don't forget, the adult Peter we see at the end is from an erased timeline. The past of the new timeline does not affect his personal past.
    – Izkata
    Aug 7, 2014 at 23:23

@Izkata - Don't forget, the adult Peter we see at the end is from an erased timeline. The past of the new timeline does not affect his personal past.

Agreed. That is, in fact, the only thing that makes sense as to how Peter and Olivia can be together in the prime universe. However, the absence of September must still have an effect in the "Peter-erased" timeline - in effect, a second Peter might be created as Walternate would have still have discovered the cure in the alternate universe in the absence of a distraction. Of course, they do not show us all that; so that is thinking too far ahead of things we should not be concerned with.

It still does not answer the question of why Walter would send the letter so far ahead of the implementation of the plan though, especially when he did not have many of the important elements of the plan - Ex: the device Olivia was sent after, the rocks Donald attempted to retrieve, the beacons (he must not have even made contact with Bell yet at his storage), etc. We necessarily have to assume that Walter did not want Peter to find that letter until everything was said and done.

Perhaps, he gave the letter to someone and instructed them to send it on a particular date and time, only if certain circumstances were met (everything being normal on that day). For that, he must have known the date and approximate time of the invasion. Knowing that the said circumstances were met on the said date and time, this person could have delivered the letter (assuming it did not exactly arrive in the mail, but hand-delivered by someone).

Ultimately, we cannot know what the writers were thinking. They could have deliberately left these issues open-ended for us to figure out, or they did not really think certain things through.


Walter from reset timeline knew for sure exact date when invasion started. As he experienced it.

September and he were working over plan how to stop Observers. Walter knew that if plan will work out he will be vanished away at same moment when invasion did not start. It's clear from what Olivia said that since day of invasion until day when they ambered themselves some time has passed, which means that it was not one and the same day.

Which means that Walter did not send out tulip exactly before they got ambered. Same as he did not make video same day.

Letter sent at that point would arrive later than the date of non-invasion.

I think that Walter sent tulip the day the invasion started. As he had hope. Also imagination and vision of that new time line appearing after reset.

Walter knew when he will disappear. Just that. Maybe he left a reminder to himself and he in the past put that tulip to Peter's door.

Walter saying: I was here one moment and next I am vanished. This sounds as a thought of Walter about himself on that day when invasion didn't start if he just got some reminder. Like he thought of himself as some Fringe case... :)

Like his not having the memory of the awful future from reset time line was anctios that his plan worked.

I think that idea of it is that Walter was an outstanding man.


I agree with user1234 above. Walter knew for sure the exact date when invasion started. I saw the end of Season 4 again, and saw something I forgot about. In the ending scene of the last episode, September comes to Walter and tells him that "They are coming!" Two-to-three years pass between that time and the invasion. This is proof that Walter definitely knew the date of the invasion, if not the exact time.

It is highly likely that Walter and September started planning everything out and made the videos far in advance of the date of the invasion. September must have played a central role in all of this. During that two-to-three year period, September must have got captured by his fellow team of scientists who must have removed the device from him. I do not see Walter being able to accomplish any of this without September's help.


I just finished watching the entire series on Roku, and had the exact same question. After reading all the responses and thinking about what I saw the last 2 months, I think there are a couple answers to this, unless some new plot lines will be thrown into Season 6/new movie(we can only hope).

Answer 1) What must have happened is Walter mailed the envelope a few days before the observers arrived for their takeover. Walter knew the invasion was coming imminently, and knew the plan by that point. He knew the time line would be reset, if he was successful, so he mailed a letter to Peter a couple days before the invasion timeline start-point, timing it such that it would arrive AFTER the observer invasion. At the time of the letter writing, Walter also knew he would make a tape during the last couple days. So he sent the letter before the invasion, and made the tape right before the "ambering". Sidenote here: September picked up the letter in the observer invasion timelines (vs Peter getting it in the mail), and held onto it until the very end, right before the plan was implemented. That is whey September had the letter in the last episode.

Answer 2) Walter sent it from the future. As Michael knew everything about the observers (plus some), this is very plausible.

I tend to think answer 1 is probably what the producers were thinking.


But the more possible thing is the letter that he sent the white tulip was given to him from September from a timeline that never existed. i think that the Observers was only wiped just as the invasion started because grandfather paradox saw too much variables that September created to wipe completely so some Observers are living outside of time and this brings me to Season 6 that they get Walter back 2167


My pondering thought is - The letter that Walter left for Peter, had some kind of quantum entanglement attached to it. Thus it's meaning and purpose isn't affected by shifting timelines, so Peter when he sees it, remembers future events (that technically he now doesn't experience)...

  • I know you say this is a pondering thought but do you have any evidence at all to back up this theory that you could edit into your post?
    – TheLethalCarrot
    May 6, 2020 at 13:21

What all of you are missing is that if September's existence is undone he never would have interrupted Walternate's creation of Peter's cure; which is the action that set in motion the entire chain of events.

Without that Olivia never does the Cortexiphan trial, the purpose of that was to get Peter home.

Almost all of Walter's and Walternate's behavior after that was reactionary to the loss of Peter and that affected two universes and all of creation.

Its a Paradox. While the Observers calculated a way to exist prior to their creation they failed to include ALL of human nature. For Etta, Michael, and September to exist and the future people to exist in 2167 they would have to figure out a way to undo the invasion, not the creation of the invaders. Basically Septembers's existence nor interference cant be undone.

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