User blog comment:Samium/Nico Robin, human in a world of characters (Essay)/@comment-24850639-20170106195852/@comment-24850639-20170106225502

First off, I'm not talking about the scene where she joins, I'm talking about the scene in the treausre room as Robin sits up against the poneglyph. Robin had literally given up on her life, and was ready to die right then and there because she felt she was all alone with a dream that had too many enemies. Luffy made the decision for her that her life was worth saving. Luffy had nothing to gain by saving her life, and at that time he wasn't even thinking about her as a crewmember. At the end of the day it was Robin who made the decision to join the crew, Luffy didn't recruit her, which is the ONLY StrawHat you can say that about. So honestly that nullifies anything you can say about Luffy pursuing her for any kind of selfish reasons, or pride. Historian/archaelogist was never any kind of role that Luffy considered absolutely essential to his crew either, so he pursued Robin because he cared about Robin. It never had anything to do with what she could offer him. He was even warned by Aokiji that he should drop her, and almost died over it, yet never allowed himself to think any less of her for it, nor allow the crew to do so.

You keep bringing up Luffy's intelligence level like that matters for some reason. If Robin cared about his level of smarts, then she wouldn't have stowed aboard his vessel and decided to spend the rest of her life with him. Robin implicitly trusts Luffy because Luffy has demonstrated on several occasions he loves his crew unconditionally, and that he will go through any obstacle to help his friends. You don't need to be intelligent to demonstrate that you're a good person who can be trusted, or that you have someone's back. In fact, as Kaido pointed out, it's his simplemindedness that makes all of his actions THAT much more sincere. Luffy is always going to say and act how he truly feels in his heart, so if he tells you he cares about you and that you can count on him, then you're GOING to believe it, because you know that what you see is what you get. It because Luffy showed that he cared about her so much, that she dedicated herself to giving her all for him.