Diallo is a character in 80 Days. She is an African griot- someone who maintains the oral history of her people through stories and songs. Aboard her contraption, the Ghazal, she travels across the continent spreading the history she has been tasked with protecting through nothing but her own voice and her many instruments. Currently she is traveling from Timbuktu to Marrakesh on a diplomatic mission; she has been assigned to act as an envoy to the Moroccan court by Sultan Tall of the Toucouleur Empire, but is happy to bring Fogg and Passepartout along for the ride.
Also aboard the Ghazal is Khalid, who seems to have some kind of relationship with Madame Diallo. By snooping around, Passepartout can spy the two of them working on something in secret together, although he cannot see what it is. Returning to where he saw them before he can discover Aissatou, an automaton who by all accounts seems to be sentient and think for herself. She will ask who he is and if he is a friend of her mother before saying that she feels cold and needs her mother. Diallo will be angry at Passepartout for putting his nose where it doesn't belong before running off to help her daughter.
Later, Madame Diallo and Khalid will explain to Passepartout that because she is infertile and can therefore have no children of her own to continue her legacy as a griot and make sure her people's history does not die out, she decided to build herself a daughter. The two of them built Aissatou together and, using a special script that she invented herself, Madame Diallo engraved Aissatou a shard that would give her a soul. She does not trust the Artificers Guild, believing that if they knew about her daughter they would take her and examine her piece by piece to discover how a lone African woman did what they still haven't managed to do. In order to protect Aissatou she keeps her a secret from the rest of the world, and now that Passepartout knows she offers him Aissatou's Shard, a deep blue control shard that used to be her brain before she got a new one, in order to buy his silence. Before leaving the pair in Marrakesh, Khalid asks Passepartout again not to betray Diallo and her daughter.
If, in Madras, Passepartout had a run in with the Sisters of Didacus and offered to help them find an automaton with a soul, he can use the telegraph office in Marrakesh to contact them. There, after checking his morals at the door, he can betray Madame Diallo and her daughter by either sending the Sisters Aissatou's Shard that Diallo gave him or by giving them the location of Aissatou herself, after which he will receive a message from Sister Panimalar, containing a large reward and thanking him for his help.