#sergei in that diner getting more and more despondent and has to be kicked out when it closes

[air-mechanical]

When Sergei's waiting for Margo to show up in the diner, how many times did he think to himself, 'I showed up at her doomsday club before 11.59. I was early. She's not even on time.' And then hate himself for thinking anything negative about her.

He brings his science magazine with him not only to pass the time, but to prove to Margo that his intelligence hasn't drained away. That he's still sharp and inquisitive and while he can't match her current knowledge any more, he still keeps up to date with space industry news. He still knows people in it. He's still worth knowing.