Re:ZERO -Starting Life in Another World- Season 4 Episode 16 marks an important moment for Subaru, as it has built up to this point since the episode where Subaru had his amnesia. The episode is based on the idea of the amnesiac Subaru exploring the Book of the Dead.
In this sense Re:ZERO -Starting Life in Another World- Season 4 Episode 16 is different in how it finally resolves the mystery of the similarities between two versions of Subaru. It can be noticed that the episode shows that amnesiac Subaru and original Subaru are the same person who has the same past.
A Painful Journey Through the Books of the Dead

In the beginning of Re:ZERO -Starting Life in Another World- Season 4 Episode 16, Subaru is shown pulling out books from the archives in search of something that makes the 'real' Subaru special. He experiences many of his deaths, such as being killed by Elsa and dying in a dark alley in his attempts to find something that makes him special.
What his journey results in, however, is just pain and suffering, and the sequence shows the audience how much suffering Subaru has been through in the show by showing flashbacks from earlier episodes.
The Two Subarus Finally Meet in Re:ZERO -Starting Life in Another World- Season 4 Episode 16

Re:ZERO -Starting Life in Another World- Season 4 Episode 16 brings a highly anticipated moment when the amnesiac Subaru comes across the original Subaru. Filled with rage and fatigue, the amnesiac wants to know how they differ, as he is convinced that there should be some contrast between a hero and a loser.
The original Subaru offers a simple answer, claiming that love for those around him inspires the original Subaru to go further. This moment becomes the main part of the episode that results in the line that has now become iconic.
Rui's Breakdown Inside the Corridor

Re:ZERO -Starting Life in Another World- Season 4 Episode 16 also features Rui Arneb, who split into two parts to be able to experience the memories of Subaru herself. This splintered version of Rui takes everything to the next level and suffers a complete mental breakdown after having lived through all his death experiences.
The original Rui does not understand this breakdown and accuses her fragmented self of accumulating stolen memories. This leads to chaos between the two Ruis, with Subaru refusing to show sympathy towards them.
Subaru's Return and Emilia's Reaction
At the end of Re:ZERO -Starting Life in Another World- Season 4 Episode 16, Subaru rejoins the battle against Lye with new memories. He interrupts Emilia and calls her by the name "Emilia-tan," which he had lost earlier.
Emilia's reaction to hearing the name again is an essential point of Re:ZERO -Starting Life in Another World- Season 4 Episode 16, as it marks the moment she realizes that her knight is back.
Subaru continues the episode by returning to his signature pose, serving as a symbol of the fact that the character from the beginning of the season is himself again.