Originally Posted by
Plushie
Wow. I would not even bother trying if I didn't know the language. =O Now that's dedication!
To answer your questions:
4th admires her because she is so different. She is independent, talented and she has a good heart. As a prince, he is used to seeing women trying gain favour in the imperial court using any means necessary, all in the hopes of trying to gain favour etc etc. But Ruoxi is different. She doesn't care for all of that. Instead of using her talents to get ahead, she uses them to help a friend (Min Min). She is also fiercely loyal and brave as shown in the incident where she races Min Min even when she can't ride a horse well at all. Thus 4th became intrigued by her and cannot forget her.
In regards to the hairpin and necklace. Earlier in the story, Ruoxi does return the necklace and hairpin to 4th as an rejection to his advances. In which, 4th does accept her rejection and decides to let her be. However, as 13th tells Ruoxi, the dance choreography and horse race incidents caused 4th to change his mind: He's not letting her go after all. It's the first time where 13th saw 4th ever look a bit flustered and unsure of himself (about changing his mind about letting Ruoxi go), when usually he is such a calm person and wouldn't go back to change something he already decided on.