FIRST OPTION:
Embry wasn’t thinking much at this point. Just speaking. He drove aimlessly and much too fast. As far as he could from the sad scene. The radio was off and he wouldn’t be turning it on. He wouldn’t insult his memory that way.
Alone in the car the questions were spilling out. More than he had said all week. He was only vaguely aware of the sound of his voice. He barely heard a word.
“It's been six days. Where do I go from here Shawn?
“Why aren't you here, Shawn?
“Have you really been gone so long? Why don't I remember your voice, Shawn? Why did you have to take so much with you, Shawn?
“Am I all that's left?”
SECOND OPTION:
Shawn and Embry were identical twins. But Shawn and Embry were not two halves of a whole. Shawn was everything. And Embry was his faithful shadow.
“Let’s do it!” Shawn said, his smile was exuberant, mischievous.
Embry shook his head and backed away.
“Oh come on! You haven’t been on date since the last one of mine I sent you on.”
“She knew.”
“That’s because you were you and not me.”
“I am me.”
“You have more fun as me.”
"I don't."
I find that the period between 'He drove aimlessly and much too fast.' and 'As far as he could from the sad scene.' breaks up the rhythm too much.
Also, I have no idea why turning on a radio would insult someone's memory. Perhaps you were referring to Embry's memory of ShawnShawn? At any rate, it is an unfathomable sentence that annoyed me a bit.
Your premise sounds interesting. Keep writing!
I tend to like openings that throw me right into the action, as long as it gives enough background I don't get lost. So I'd write it like this, giving the "telling" part after the hook line. It makes people read through the explanation to find out what "it" Shawn is talking about, and by that time they should be curious what is going on:
“Let’s do it!” Shawn said.
Embry shook his head and backed away. Shawn and Embry were identical twins. But Shawn and Embry were not two halves of a whole. Shawn was everything. And Embry was his faithful shadow.
“Oh come on! You haven’t been on date since the last one of mine I sent you on.”
“She knew.”
“That’s because you were you and not me.”
“I am me.”
“You have more fun as me.”
"I don't."