Our Bridge Baby
It is established in Death Stranding that Sam and BB-28 are separate individuals and that the memories we see when Sam connects with BB-28 are actually his own from when he was still a baby.
Though, what that has to do with BB-28 remains to be seen. Did connecting with a Bridge Baby trigger some part of Sam’s memories that made him see his own past or do Bridge Babies have some weird telepathic network that allows them to all share memories?
Also, how did our darling Lou end up with the exact same trinket that Clifford Unger put on Sam’s pod over 20 years ago? In the final World War Beach, BB-28 reacted to Unger singing the song he sung for Sam as if he had sung it to him personally. Though, we know that he didn’t because he sung it to Sam.
It could be that Sam’s memories were the ones bleeding into BB-28 but that still doesn’t explain the trinket.