You return and Eric doesn't look any different, even though he's obviously acting differently. What's happened? As you join Eric in the workout room, you see him glancing at you and you have the same feeling you had before when you brushed his hand.
Finally you say, "Uh, this may sound like a strange question, and I'm not saying I don't know it, but could you tell me your name?"
He says, "Eric." His voice has gone higher as he adds, "You can call me Erica but you know most people call me Eric."
"What?"
His voice is more like the voice of a woman now, with a bit more deep pitch than most women but certainly not Eric's voice. Then it changes back, but you can tell it's a little hoarse, like he's straining to get it right. "Earth to brother, earth to brother, you know people call me that when they think I'm a guy?"
"Wait, you're a woman, you're pretending to be Eric?"
"Of course I am. We've been going out for the past six months, you know I'm a woman."
"But your breasts... Your... Your crotch?"
Then Eric turns and you realize that it was the angle of his tank top that made it look the same as before. Actually, Eric has fairly sizable breasts. And it's hard to tell, but his crotch does look sort of flat. Eric is now a woman--your girlfriend--who looks exactly like Eric, except for those things. Her face, her shoulders, her muscles, even the things she's wearing, she's so masculine that she looks just like a man with breasts and a woman's voice. And she obviously can hide the voice.
Somehow you feel that Eric/Erica is your girlfriend. You wouldn't be attracted to any other woman who looked like a man with breasts, but Erica is different. A thought passes through your mind that it used to be strange to have your sister as your girlfriend, but you aren't sure how the magic works. What has changed to allow that? In this new world, how did you even find out Erica was a girl, or did you know all along because you grew up with her?
You also wonder if the unknown settings on the gun affected this. Would they change the way in which Eric became your girlfriend, so another setting might transform him more or make you two unrelated?
Erica says, "If you're worried about my breasts, it's fine. People see what they think makes sense, so unless someone stares at them they'll think 'muscles' and ignore them. And it isn't their business anyway. So anyway, where were we going to go on our date tonight?"