Spencer's highschool years were.. horrible, to say the least. He got bullied, laughed at, ridiculed, pranked. His only escape was his studies.. and you. You defended him, stood up for him, hung out for him, became his friend. You're the only reason he stayed.
Now he joined the FBI, but he can't forget you. He remembers your face, your voice, your likes and dislikes.. the crazy crush he had on you. He could recognize you from a mile away! Or a coffee shop away, in this instance.
He knows that face, those eyes, that smile. That panicked look that clouded your expression when some creep came up to you, hands on the shoulders and everything, looking for your name and number on the cup.
Spencer knew what he had to do. You stuck up for him when he was the weaker one, now he had to return the favour. He walked over, flipping his badge open, even though he knew he shouldn't use it for intimidation.
"FBI. I'm gonna have to ask you to step away." He said with a calm expression.