#but in the context it's clear that Henry is lovingly teasing his sister

[bethanydelleman]

Jane Austen associating the word "rational" with women over six books:

Do not consider me now as an elegant female, intending to plague you, but as a rational creature, speaking the truth from her heart. - Elizabeth Bennet, Pride & Prejudice

“But I hate to hear you talking so like a fine gentleman, and as if women were all fine ladies, instead of rational creatures. We none of us expect to be in smooth water all our days.” - Mrs. Croft, Persuasion

She dearly loved her father, but he was no companion for her. He could not meet her in conversation, rational or playful. - Emma Woodhouse, Emma

“Oh! never, never, never! he never will succeed with me.” And she spoke with a warmth which quite astonished Edmund, and which she blushed at the recollection of herself, when she saw his look, and heard him reply, “Never! Fanny!—so very determined and positive! This is not like yourself, your rational self.” Fanny Price, Mansfield Park (we know that this is very much her rational self, also after a marriage proposal)

Elinor agreed to it all, for she did not think he deserved the compliment of rational opposition. -Elinor Dashwood, Sense & Sensibility

You talked of expected horrors in London—and instead of instantly conceiving, as any rational creature would have done, that such words could relate only to a circulating library, - Henry Tilney, teasing his sister, Northanger Abbey