Gokudera would actively avoid this guy over a bad first impression, but given this is Duplicity, he should maybe he a little more lax.

He's not looking at Aki, just spacing off for a moment, looking as if he doesn't have a single care in the world. Gokudera lights his cigarette and moves to offer it, turning slightly and finding Aki leaning in towards him. On reflex, the teen presses at the lighter and holds a hand against it to shield the flame from wind or water, leaning in as well so he can make sure Aki can light up.

In hindsight, it may have been cool to light Aki's cigarette with the burning tip of his own, but the jury is still out on how he feels about this guy. Now that they're facing each other and the dark-haired guy is relaxing and his boxers cling, green eyes widen and then he glances aside. He's no pervert. He's just a horny teenager.