If you take a look at Brimstone's Agent Card - it's a silhouette of himself carrying a fallen person, titled "No one left behind."

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NOW, if you take a look at the new agent, KAY/O's agent card...titled "Memory Log"

It's the exact same position & silhouette!

And who was the first agent that was paired with KAY/O's reveal in the trailer?

Brimstone saying "Get a move on Agent"

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There's a lot more of Easter eggs hidden within the game at the moment so will be unravelling them soon.

EDIT: woah! thanks for the hugs & coins - love to see what RIOT will have in store for us, perhaps a new cinematic lore with KAY/O ?