Character Analysis
Bibi frequents the café where Tamina works, and she spends some part of each day sitting on a stool (with her pee-drenched, neglected baby crawling around on the floor) and chewing Tamina's ear off. She's not interested in Tamina's past. Bibi is interested in Bibi.
To be fair, Tamina is not that into Bibi, either; Bibi only becomes interesting when she says the word "Prague." At that moment, Bibi becomes for Tamina the portal to her past life. But Tamina knows that there's no real friendship between them. She knows that she'll have to do Bibi a solid favor to get her to reciprocate.
Bibi's desires are shallow: she wants to write a book (a novel? a thriller? a biography?), but she doesn't want to work too hard at pesky things like character development. What she really wants is to talk about herself—just as she does at the café with Tamina:
"I often have the impression my whole body is filled with the desire to express itself. To speak. To make itself heard. Sometimes I think I'm going crazy, because I'm so bursting with it I have an urge to scream..." (IV.8.19)
Bibi is the perfect example of a graphomaniac—a person who feels compelled to write her life story because she doesn't get the love and attention she thinks she deserves from everyone around her.
Despite Tamina's efforts to impress, Bibi clearly doesn't get the memo about the importance of those notebooks; in fact, she lets Tamina down in a big way. Bibi's lightweight attempts at friendship are just another reason why Tamina yearns for the past: there's just nothing compelling to tie her to the present.