On dragons and the killing thereof

[veti]

Or he may have never thought to care what happened to the dragon.

My point exactly.

You're making multiple assumptions I won't grant. That Roy knew the duration of Vaarsuvius' Suggestion spell (he was shocked when Vaarsuvius said it was about to expire).

He knew it would have a finite duration. He's an intelligent guy. Is it that unreasonable to assume it might have occurred to him, during eight hours of nigh-terminal boredom, that a more long-term solution would be needed at some point? And having thought that far...

That he knew Vaarsuvius planned to kill the dragon any time sooner than Vaarsuvius doing so.

See above. What do you imagine he thought Vaarsuvius was planning to do when she was restored? Loot the dragon's hoard and walk away, leaving its righteous vengeance contained only by a spell that was just about to run out?

That he could actually have any sort of conversation with Vaarsuvius, bearing in mind that the dragon would have had to translate for Vaarsuvius, and that the dragon might well have broken free of the Suggestion had Vaarsuvius said that s/he intended to kill him.

He could talk to Vaarsuvius just fine - the dragon would only have to translate V's replies. And for Roy to reason that "the dragon might break free of the suggestion if V mentions that she intends to kill him" - would require Roy to suspect that V, in fact, did intend to kill him. As well as assuming that V was incapable of communicating with him without cluing in the dragon.
"What are we going to do about the dragon?"
"I was thinking along the lines of what Elan did with Dorukan's dungeon."

That, if Roy could have had a conversation with Vaarsuvius, his not doing so is indicative of a choice not to oppose Vaarsuvius killing the dragon, and not him stupidly not putting the "I can talk to the party member I've been ignoring ever since he got Baleful Polymorphed now" together.

This one, I have to grant you. But it just brings us back to proposition 1: that Roy didn't really care what happened to the dragon, so long as the OOTS weren't on its menu.

I suspect you might have a vested interest in reaching a "no member of the Order thought it was wrong to kill monsters at that time" conclusion.

And I suspect you have a vested interest in reaching a "Vaarsuvius's instinctive alignment is Thoughtless Evil" conclusion. But even if we were both right - what difference would that make?