What can we say abut Astrid other than she "only exists to feed obsession" (1.5.21)?
Actually, we've got a lot more to say.
Astrid, it's true, is an alluring beauty who stops people in their tracks. But she is so much more than this. She is passionate, savvy, and dedicated her family—well, dedicated in a way that makes sense to her. Sadly, the life people believe Astrid to have isn't the reality for her, and it's led to a lot of heartbreak.
Astrid, like Nick, is from legendary stock. The two are cousins: her mother is Nick's father's oldest sister, aka Felicity and Phil. Not only is Astrid akin to the wealth of her grandmother, Shang Su Yi, but her father, Harry Leong, is considered "one of the kingmakers" in the Singaporean government (2.16.71). The two branches of Astrid's family control the entirety of Singaporean commerce.
While Astrid isn't an eldest son who stands to inherit the fortunes of either side, she has tremendous wealth to her name. None of it is under her control, other than the means by which she spends it, and that doesn't seem to be enough to strike a balance: "Twice a year, when the family sat down with their business managers […] she would notice that her personal accounts always increased in value, sometimes to an absurd degree, no matter how many couture dresses she had splurged on the previous season" (2.1.29).
Okay, so we know Astrid is pretty rich. And she's good at spending the money. One of her greatest skills is finding items of exceptional taste and exclusivity. Multiple times throughout the novel she impresses other Richie riches with her dresses and jewelry, even disappointing some when she doesn't show up in a new couture dress. She discovers her love for shopping from her first love, Charlie Wu, in Paris at 18, and "honestly, it was better than sex" (3.9.60). This adrenaline rush from shopping keeps Astrid afloat at times: after she learns of Michael's mistress, she drops over a million dollars on jewelry…in 20 minutes.
Here's what's special about Astrid. Despite all this money and this love of spending it, Astrid is surprisingly…normal. Okay, normal is relative. But even her husband, Michael, noticed on their first date that she wasn't as seow cheich (high maintenance) as he had been led to believe" (2.5.31). Even at the social event of the century, the Khoo/Lee wedding, Astrid plays down her own wardrobe rather than be the center of attention (this could be because Michael wasn't with her, but let's give her a little break there).
But what we really see in Astrid is her unwavering devotion to Michael. Despite believing that he is cheating on her, and potentially has been for years, she still wants to forgive him, to work things out for the sake of their family. More so, when Michael breaks down, revealing that he can't live up to being married to everyone's idea of Astrid and her judgmental family, she says she'll throw it all away to keep him.
Though her storyline is secondary in the novel, it plays a critical role: Astrid is kind and down-to-earth like her cousin Nick. And was painfully unaware of the toll her family would take on an "outsider" (1.8.19). Hers is the lesson Nick must learn in order to keep Rachel.