Well, it's an open question of exactly how much would happen, and how non-con it would be.
On the How much would happen? front, even if Sam stopped it before actual sex happened, it'd still be fairly traumatic for Sam ("My possessed brother tried to rape me" is less traumatic than, "My possesed brother raped me," but still BAD) and enough to inflict horrifying levels of guilt on Dean.
On how non-con, I'm not sure, but maybe something that was more like heavy pressuring than an out-and-out attack? And Sam went along because part of him kind of wanted it?
Of course that would result in crushing levels of guilt for both of them.
no subject
On the How much would happen? front, even if Sam stopped it before actual sex happened, it'd still be fairly traumatic for Sam ("My possessed brother tried to rape me" is less traumatic than, "My possesed brother raped me," but still BAD) and enough to inflict horrifying levels of guilt on Dean.
On how non-con, I'm not sure, but maybe something that was more like heavy pressuring than an out-and-out attack? And Sam went along because part of him kind of wanted it?
Of course that would result in crushing levels of guilt for both of them.