I was asked for my thoughts on Robert, Chris and Trevor 'just existing in the same space'. It's hard to know where to begin with these three!
I suppose the short version of Chris and Robert's relationship is that they're acting rivals with some very weird things going on underneath. Robert views Chris simultaneously as his enemy - the unreasonable, unqualified director standing between Robert and true acting greatness - and as his closest friend. Chris views Robert as a bomb that could at any point destroy everything around him. There's conflict, but there's also respect; the two of them strive to outdo each other on stage, and Robert explicitly considers Chris one of the better actors in the company.
By contrast, there's no respect between Robert and Trevor. From Robert's perspective, Trevor is not an actor, so what does he add to proceedings? However, despite his lack of respect for Trevor's role, Robert does trust and rely on Trevor, and will call on him for help in an emergency.
We don't see a lot of Trevor's attitude to Robert, but I feel Trevor probably doesn't have a lot of time for him, going largely by the fact that, when Robert calls for his line during his death scene in Haversham Manor, Trevor's response is 'Just die already.' Other people have also made the interesting observation that, in Summer Once Again, Trevor is nowhere to be seen: because Robert decided that a stage manager was unnecessary, or because Trevor doesn't want to support Robert as the director?
That said, I was recently rewatching the footage from Dennis's birthday party in the televised version of A Christmas Carol Goes Wrong. There's a point where Jonathan tells Chris, 'I think Robert would make a great leading actor.' I'd never noticed before, but Trevor nods at that, almost imperceptibly! So perhaps Trevor does have a little respect for Robert, or at least for his acting ability.
The main impression I have of Trevor and Chris's dynamic is that Trevor works very hard for Chris but also finds him frustrating, because Chris has a tendency to take him for granted and push him well beyond his job description. Trevor can be blithely destructive in a way Chris finds stressful, but can also sometimes act as a grounding voice, perhaps because he's not an actor and therefore isn't as intensely invested in their productions as most of the others.
When you put Chris, Robert and Trevor in the same space, I think the main dynamics that emerge are:
Eventually, everyone explodes.