"Then it's worth a try."

Going to another world, just so Astarion can have his sunlight? The proposition is unquestionable. He'd do more impossible things, throw himself at every terrible challenge, if Astarion needed it.

"Now? Or would you like rest?"

Fenris suspects, strongly, that now that Astarion has his mind set to the idea, it will be all that he is interested in accomplishing.