[s3e22] The: Day We Died

: Her death at the hands of Walternate serves as the emotional catalyst for Peter and Walter to "cheat the rules of time".

“Walter's revelation about the source of the machine parts, how they got inserted into the past, and what Peter needs to do in order to unravel the future was epic in its scope. This was a classic science fiction narrative...” Den of Geek · 14 years ago [S3E22] The Day We Died

“I felt they handled it pretty elegantly - Peter was meant to die as a boy, and the best bad option for fixing the universes was the one he chose at the end of the episode.” Reddit · r/fringe · 1 year ago 'Fringe' season finale recap/review: 'The Day We Died' : Her death at the hands of Walternate

: How the episode resolves the "First People" mythos by revealing it as a temporal bootstrap paradox, where Walter’s future actions are the literal cause of the past he tried to solve. : His presence in the prime universe as

: His presence in the prime universe as a leader of the "End of Dayers" reflects a tragic symmetry; he seeks to make Peter feel the same pain he felt when his world was stolen.