They're two sides of the same coin when it comes to the abuse they've endured. When Astarion reveals his past to Orryx, the tiefling is able to recognize that defensive charm/humor for what it really is. He himself had to put up emotional walls to get through the years of abuse he endured, too. Even if that wall was a bit different.
That gruff exterior of his would soften when the two are alone. While Orryx is usually very forward about what he wants, he would let up on that to let Astarion set the pace more often than not. He might respond to Astarion's flirtation with subtle ways of checking the vampire's intentions, rather than boldly flirting back. This is, of course, all AFTER he finds out about Astarion's past.
Orryx desires and craves emotional connection with physical intimacy. He cannot get off if he can tell his lover isn't feeling the same way as him. His arousal is directly tied to that. He had enough meaningless sexual contact when he was used by Bhaal. Once he senses that attraction is there, he wants to love, and be loved back. That means that if he picks up on Astarion being tense toward what's happening, or if Astarion tells him off, backing off would be his natural next move. Seeing Astarion's discomfort would be reliving his own pain, too. Their shared trauma would create a profound, protective (sometimes overbearing) empathy in Orryx that goes beyond his typical dynamics with a relationship.
Still, Orryx isn't perfect. He would struggle a bit. He wants Astarion, physically and emotionally. Instead of pushing when he's shut down, he forces himself to create space for Astarion to fill when he's ready, giving him room without abandoning him.
During moments of rejection, Orryx fucks off to train, or do something else physical to release any pent up tension he has. As time goes on, he would get better at staying to reassure Astarion he's not just a sexual object to him. But earlier on he just removes himself and leaves the ball in Astarion's court.
If Astarion is triggered by anything during sex, Orryx first instinct is to stop. Like I said before, the emotional side of things is huge for him, so he's very sensitive to keeping in tune to that, even when they go at it sloppy style. His entire gruff character is built around becoming the man he needed when he was in the midst of the Bhaalist cult, and that's what he becomes in moments like that with Astarion. He becomes the man he would've needed then, drawing from his own desperate need for safety during his years of captivity. Once again, he's not perfect, but he would try his best to ground Astarion in those moments, reminding him where he is and who he's with.
Talking about those moments would probably be beneficial, but Orryx likely wouldn't bring them up often, after the fact. Once again, it would feel like hashing out his own trauma.
The two of them heal their relationship with sex together as time goes on, but it does start out a bit rocky in terms of how they recover from those moments.
