Gentleman Cambrioleur

The problem is they suddenly introduce her as the linchpin of the entire plot of Part 3 while giving her no actual development as a character. As viewers we basically just have to accept that Assane would drop everything to rescue her but we have no real context for who Mariama is as a person or what her relationship with Assane looked like before he and Babakar left Senegal.

This was something the first couple of episodes of Part 1 actually did really well with Babakar. Through only a few flashbacks you saw his relationship with Assane AND how he was treated horribly by the Pellegrini family, which made him a sympathetic figure and it made complete sense why Assane would want to avenge him.

With Mariama, this would have helped a lot, but in contrast really all we know of her at the time Assane learns of her kidnapping is that she voluntarily cut herself off from him when he was seventeen. That's it. This makes it much harder for the audience to understand Assane's need to rescue her beyond generic "mommy issues." We also don't really get to know her much at all since in the present timeline she's mostly offscreen until the very end.

This gets more problematic when Assane starts sacrificing people he's objectively far closer with (and whom the audience cares way more about) in order to save his mother. The Ben betrayal is the obvious one but there's also that moment when, even though he'd explicitly promised Claire that he'd be there for Raoul's basketball game (and was literally the team's coach) he goes to meet his mother at the metro station instead. This despite the fact that Assane knew that Claire and Raoul were being stalked by Keller's henchman.

In the end, the show doesn't give us nearly enough context for why Assane would be so fixated on a woman he hasn't had any contact with since he was a teenager. And while it's possible to interpret Assane's behavior somewhat sympathetically here through the lens of childhood trauma, that just makes Mariama look worse for having abandoned him. It's basically a lose-lose: either Assane is acting unreasonable, or Mariama is cynically exploiting his abandonment issues to save herself because she got into an avoidable situation (don't accept rides from random people lmao).