given you a number, taken away your name (слэш)

As Tony behaves more erratically, S.H.I.E.L.D. sends in Steve as an undercover agent in S.I. to be Natasha’s back-up. Except Steve is really, really not cut out for this undercover business.
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Before the lift’s doors closed, Stark suddenly grinned and said, “Call me Tony. Have a better rest of the day, big guy.”
Awkwardly, Steve lifted his free hand and waved as the doors slid shut between them.
What...what was he doing? Why was he waving? Steve hurriedly put his hand down and turned around sharply.