One night, while on holiday in Devon, I had a dream that I followed Robert Grove into a bathroom stall in a shopping centre and attempted to solicit sex from him. He just stared at me and left. I can't believe I was rejected when my approach was so normal and irresistible.
As a consequence of this, I spent a concerning amount of the next day thinking about sex with Robert Grove.
My first instinct was that Robert would be a selfish lover, because, well, he's a selfish person. However! What Robert really wants to do, at all times, is put on a performance and get a warm reception from the audience. In bed, you are his audience, and his main interest is getting a good response from you.
This means he will pay attention to your pleasure in bed! If you're not visibly and audibly enjoying yourself, he's not satisfied. Unfortunately, he is ungracious about this; if your response is not to his satisfaction, he will call you a philistine and sulk.
While Robert is likely of the opinion that thrusting harder equals better sex, you can probably get him to do just about anything if you frame it as a role you'd like him to perform. He is willing to perform oral sex, but will grumble that he prefers speaking roles.
My extremely inexpert assessment of the other members of the Cornley Drama Society in bed:
Annie: Great! Bold and enthusiastic, invested in both of you having a good time, introduces you to some fun new fetishes.
Sandra: Sandra and Robert are both very self-absorbed, but, unlike Robert - who seeks to bolster his ego through your reactions - I think Sandra's mainly interested in her own pleasure in bed. She knows what she's doing, though, which is more than can be said for much of the society. You'll probably still have a good time.
Max: Clueless but enthusiastic. Is, like Robert, very invested in you responding well. Probably not bad overall.
Dennis: Clueless and terrified. He's either dreadful or, much to the surprise of both of you, turns out to be the best sex you've ever had.
Vanessa: Has drawn up an agenda for your sexual encounter, assigning time slots for each specific act, and will become very stressed out if you deviate from it. She'd probably be good if she relaxed a little! She will never relax.
Trevor: I have no idea what Trevor is like in bed, and I find it slightly alarming to contemplate. If it's anything like the way he drives, you are in physical danger.
Jonathan: N/A. You will never sleep with Jonathan. You can try! But somehow the two of you will always be prevented from actually performing the deed. He's probably the best lover in the drama society, but you'll never know.
Chris: Terrible. The worst of the lot. He will try! He will fail. Do not sleep with Chris Bean.
I mean, you can if you want to. It's not that bad; he's just deeply repressed in a way that is unlikely to mesh well with 'hey, it's time for a lot of intimacy and physical contact.' The experience is likely to be disappointing, rather than traumatic. But it's going to be so disappointing.
What about putting the members of the Cornley Drama Society in bed together? One way or another, it's likely to, well, go wrong.
The trouble with putting Chris and Robert specifically in bed together, and I say this as a fan of the Chris/Robert pairing, is that I feel Robert is romantic and vanilla in bed, whereas Chris has a masochistic streak a mile wide and just wants someone to tie him up and whip him. I attempted to write fanfiction in which Chris asks Robert to hurt him, and it never got anywhere because Robert's response was just '??? that doesn't seem right.'
Robert will hurt you unintentionally in the course of acting, and he'll hurt you deliberately in order to steal your role, but he just doesn't think the bedroom is the place for that sort of thing. Which is, I'll be honest, Robert, extremely inconvenient for me personally. Just let me write these things!