Ok, so I read this book in my pre-GR days, but it's still a favourite. It does require a certain suspension of disbelief in order to get the whole thing rolling though: a rich guy basically arranges to have his old college best mate stranded on a luxurious island with him, and coerces him into sex. But it's also more than that, promise.
There are some elements of dub con here, in that David is totally reliant on Ethan in this situation, and Ethan is pushing him way faster than he wants to go. Although, if Ethan didn't push...no story.
The sex scenes in this book are absolutely mind-blowing. Just fucking awesome, because they are filled with so much emotion -- and no, not the lovey-dovey kind. David's fear is palpable. Ethan's pushiness and his patience sometimes fall out of balance. He's not as in control as he pretends, and David realises that. And sometimes you hate Ethan for pushing David, and sometimes you want Ethan to push harder.
But the hottest scene in this, for me, wasn't even one of the sex scenes. It was when Ethan is hand feeding David. Holy. Hell. And, given that I read this book ages ago and it still stands out in my mind, that's saying something.
And also... when David cuts his hand and Ethan treats it. So much subtext going on there that my brain almost exploded with delight.
Love this book.