I was reading up about the fish in the show yesterday and stumbled on this
So far - the key/leadership symbolism is playing out exactly as it was in the dream.
S1 -Mr. Robot gives Elliot the key first. I guess this would have been when he figured out he was Mr. Robot. He also says that the key is "Made In Your Orient' - which I took to mean that fSociety was essentially formed by the events that shaped Elliot into who he is. ie his father's death.
S2 - Darlene gives him the key next - when he got out of prison, he assumes control of fSociety from her.
S3 - The point we're at now is when he comes back to his apartment to find Tyrell has the key - could be a metaphor for his input into Stage 2, or the fact that the FBI believe he's the mastermind.
S4? -Next Elliot gives the key to Angela when he finds it in the fish he's eating, and she accepts it like he proposed marriage. I feel like we're about to see this happen, especially after last week. God knows what she'll get up to with it.
S5? - She gives the key back to Elliot saying it doesn't fit - Maybe she figures out she's been played by whiter0se
Esmail might have given us the broad strokes of the story already, back in Season 1