I really like the specualtion that the trial by combat might be between Oberyn and the Mountain. Tywin calls for the Mountain, and Tyrion calls out to see if anyone will stand for him, possibly in a sarcastic way, then starts to suit up, and Oberyn languidly folds himself out of his seat and says he’ll fight for him. Nobody could tell him he wasn’t allowed.
If that does happen, that could still be in line with what Tywin really wants.
Tywin definitely is ammoral. He has principles, but not morals. They’re not the same thing. His principles boil down to “save the family line above all else.”
The other option is that this buys Tyrion time and he simply escapes. A scar-faced dwarf on the run would have a hard time hiding, though.
Varys is playing the long game, I think. Despite his nod at the throne, he can’t possibly ever want to sit on it himself - a foreign-born eunuch as King? He’d last about a second. But he doesn’t want everyone to know he’s actually a principled person doing it all for the realm. Actually, a nod toward the throne could indicate that he’s doing it for the realm, too, even if he knew that wasn’t what Oberyn would take away from it.
“I never forget anything, sadly.” What exactly did that mean?
Theon did kill two little boys for no really good reason. Sometimes, in the real world, people wish all sorts of horrors on people who do that sort of thing. It’s interesting seeing those horrors actually come to be in a work of fiction; I doubt anyone actually likes it.
Imminent grease? Was that intentional? If so, not bad. 
[quote=“Acsenray, post:69, topic:688219”]
If you’ll pardon a nitpick – “whoever has the power” (it’s the subject of the clause, not the object).
Nope, it’s the object. Subject does/gives something to the object. Not that I think it’s necessary to use whom as opposed to who these days; it sometimes sounds nicer, but that’s all.