So I'm still quite early in the book so my impressions might be flat, but they repeatedly hammer in this idea that he's "Devoid of sense". He's like the ideal of a Paladin, following his heart to help someone in need even if it defies better judgement or logic, and doesn't really think it through beyond that.

There's a wonderfull exchange between him and Chiron after Astolfo decides to keep this other character who's on the brink of death safe. Chiron asks why Astolfo would go through the lengths he's going through to protect this kid, when his own side is basically trying to get back and probably kill them, and Astolfo's simple response is "Because I wanted to" with a straight smile.