Letting a level-18 character
any leeway is downright re[edacted] when you can't be 100% certain they wont fuck with you.
And she'd
not be okay with us binding her via Yss
Indeed, if we go the
only route that would reasonably extinguish any paranoia, we would
also do basically what she did to Westerosi Lords.
Might as well feed her to Yss at that point, less moral arguments will happen at least.
And I fully understand that such ambassadors can be cooked alive (in real history, this happened), so we can not send someone expensive, but it is impossible to send a weak person to such places, they simply will not get there.
The argument is extremely weird for DnD.
There is
no stopping a reasonably well-prepared diplomat from fleeing, teleports, stone-swimming, you name it.
Unless you throw actual PCs at them, no cigar - our Diplomacy corps are actually as well-geared
IC as Scholarum mages.
And by the point of PCs killing off diplomatic parties, we can be
sure there is no point in Diplomacy and we're at war.
Why bother?
No, please don't struggle so hard to find a niche to fill with Lana and Gerion. This one is definitely not for them.