Samuel "Sam" Strand, widely known as Sam Porter Bridges, is a legendary porter and member of Bridges who plays an integral role in expanding the Chiral Network and making the United Cities of America whole by embarking on a westward expedition.

Arriving on Amelie's Beach, Sam searches for Amelie until she appears to him. She reveals to him that "Amelie" and "Bridget" are merely names of the two halves of the single extinction entity she is – her "ka" (soul) and "ha" (body), respectively. Furthermore, she reveals that Sam's expansion of the Chiral Network has bound all connected to the network to her Beach, thus enabling the Last Stranding, as has always been her plan.

She presents Sam with two choices: watch the swift ending of the world together with her "until the last flame winks out", or use Die-Hardman's left behind revolver to sever his connection to her and her Beach and postpone the Last Stranding. Sam chooses instead to embrace her, assuring her he would always be there for her as she has for him.

Amelie reveals that as an extinction entity, she has been fated to usher in the Last Stranding, and that after an agonizingly long span of solitude on the Beach, she opted to set the Last Stranding in motion in advance by utilizing the expanded Chiral Network as a catalyst.

She chooses to remain on the Beach, to spare humanity the worst of the inevitable Last Stranding and in the hope of providing life an opportunity to come out stronger from the extinction. After sharing one last embrace with Sam, Amelie pushes him out of her Beach and into his own to return to his allies.

Source: https://deathstranding.fandom.com/wiki/Sam