I think that C.S.Lewis is lampooning the sorts of teenagers who are only interested in their peer groups. You might recognise them in Lasaraleen. He does this also with Susan to some extent, where her main preoccupations in The Last Battle, are allegedly "lipstick, nylons & invitations". Yes Lasaraleen may well have met Narnians, because she segues straightaway into a critique of Susan, herself, "the barbarian Queen", the wonderful parties & the fun they have been having. This is our first introduction to not only Susan but also Rabadash & the idea he might be "madly in love with her".

However, Lasaraleen also seems the sort of young woman who cannot be distracted from her current preoccupations with parties, & with being "in love", even if someone told her that it was Queen Susan, the Barbarian, with a conquering army at Tashbaan's gates.

It's interesting that Lasaraleen is silly but not completely bad. She helps the Narnian and she is actually quite likable. She is not a villain like the more foolish and incorrigible Rabadash. Lewis gave her a personality something like Susan's, but she is more interested in Narnia as an exciting new thing. Her feelings toward Narnia aren't all bad but are rather shallow in quality.

While I think both observations about Lasaraleen's character are probably more in line with why the book was written that way, I like having in-universe answers, so.... We know that Lasaraleen has at least seen the Narnian party, and regardless of whether or not she interacted with them, she very well may have seen Sallowpad with the group. Regardless of whether or not he actually spoke in her presence, she was probably at this point confronted by the fact that the "demons who take the forms of animals" do indeed exist.

And even if she hadn't seen Sallowpad in particular, Lasaraleen seems to live in one of the northernmost areas of Calormen. You get the idea that even Archenlander visits are abnormal, let alone Narnian ones, but she's still more likely to have actually encountered talking animals (or reliable stories about them) than either Shasta or Aravis had.

To continue your point, Narnian78, I think it's also important to note that she tries to talk Aravis out of her escape - again, citing an idea that (at least in that moment) she seems to believe about demons that look like talking animals. Yeah, her "it's not nice" explanation is... lacking, but she seems genuinely concerned about Aravis's well-being.

Now that I have seen Lasalareen ON STAGE, I have a lovely image of this funloving, flighty but kind young woman.
Yes, she certainly didn't blink an artificial eyelash at talking horses!
Thanks, Logos Theatre! Having 'met' her really brings her to life, even more than the radio drama did.

We know that Lasaraleen has at least seen the Narnian party, and regardless of whether or not she interacted with them, she very well may have seen Sallowpad with the group. Regardless of whether or not he actually spoke in her presence, she was probably at this point confronted by the fact that the "demons who take the forms of animals" do indeed exist.

Lasaraleen doesn't seem prejudiced against the horses particularly though. She doesn't say to Aravis, "You're hanging out with demons? AAAAAAAAAHHHH!" She's just like, "Fancy! How exciting!" I think that really says something about Lasaraleen's ditzy personality.

Could it be that there were plays in Tashbaan with talking animals? And if you've seen one multiple times, the mystery might have been diminished.

That said, I still think I'd have a major "hang on--" moment if I were addressed by an animal. But Lasaraleen wasn't, she heard about it second hand.

This is a great topic! It makes me wonder what Lewis thinks of "young adults." Does he view them as kinda flighty? As you mentioned waggawerewolf27 he kinda discusses that with Susan in HHB. We know he loves children, but wonder if assumes that age is a bit more self centered. Not sure, just a thought.

I thought I read that C. S. Lewis disliked children. But I'm not much a biography guy so you probably shouldn't put too much faith in whatever I remember.

There were people who said he didn't know any children/ didn't get on with them.
Very silly, since he had several evacuees living in his Oxford home during World War 2.

And even if she hadn't seen Sallowpad in particular, Lasaraleen seems to live in one of the northernmost areas of Calormen. You get the idea that even Archenlander visits are abnormal, let alone Narnian ones, but she's still more likely to have actually encountered talking animals (or reliable stories about them) than either Shasta or Aravis had.

Lasaraleen, very likely, since her marriage, has been living in Tashbaan, itself, & it is to her own marital home where she takes Aravis. Tashbaan in HHB & elsewhere in the Narnia series, is roughly the equivalent there of a city like Sydney is here. Where the movers & shakers are living, where the entertainment is, & where the Tisroc's palace & the Great Temple is. Where the people who live there have the attitude that "all roads lead to Tashbaan". Where Peter Allen might have sung "I've been to cities that never close down. To New York & Tashbaan & old London Town." The residents there have done everything, seen everything, know everything, & everyone, with a history going back to Tash, credited with being the founder. . Compared to an out of towner, like Aravis, Lasaraleen seems rather blasé. But how much is it for real & how much is it showing off to a sorely missed friend who was her own age? Though Lasaraleen was a rather thoughtless person, she wasn't really unkind, & the reason she might have been ready to help her so much might have been more to do with loneliness, than at first appearance. Her husband doesn't seem to be around much.