I've been rereading the YW books as a way to prepare for AWOM, and in WAW and WH, there are two moments when Dairine is unable to understand what Roshaun and the Sun are saying.
In WAW:
It just made me think; what was Roshaun saying? Better yet, why doesn't Dairine understand him or the Sun, even with the Speech? I'm curious what you guys think, because I have no ideas.
In WAW:
"The answer was a strange low garbled roar, one she instantly recognized, since it had shocked her so when first she'd heard it. The Sun said something, and I didn't understand. But now it was Roshaun saying something in the Speech, and once again Dairine wasn't getting it. Impossible. Everything understands the Speech!" -p.201 of the hardcover edition released in the USA.

(although...hey....a sun with some sort of disability- that would be interesting. Fred certainly had enough mind, as it were, to make it possible for things to happen in the mind.) But the same concept holds- there's some fundamental grating part that Dairine can't, or won't, understand.
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