What’s lovely is that id’Artagnan is the youngest, the least experienced, the raw hothead from Gascony.
He’s also the only one who thinks about what they’re doing, or tries to use reason and logic to come up with a plan.
Meanwhile, the other three are all “Nah, it’ll be fine, we’ll just charge in shooting as usual!”
It’s a nice little nod to the book notion that d’Artagan is the best of them all and is meant to be the captain of the musketeers eventually.
I very slightly disagree here. In these situations (like Porthos being injured, being accused of murder, etc) D’Artagnan does not simply think of other options, he questions the logic of everything, the logic of his friends. It does not come from a particular genius or intelligence or talent, and even though I still think it might be interpreted as a tiny, weeny nod towards the boy’s wit in the novel, it is not exactly the case here.
I am not implying that d’Artagnan in BBC series is dumb. On the contrary, the fact that Athos speaks very highly of him in the Challenge episode is that very reference to the novel, in which Athos several times mentioned that d’Artagnan was the smartest of them all.
What I think is happening here, is that d’Artagnan is not fully attuned to his friends. Yet. Those three, the inseparables, have been friends for years. Athos has known Aramis and Porthos for 5 years and those two were friends even before that. When you know someone for that long and you share with them everything (meals, lives, danger, wounds), you tend to become connected in the way that does not require words and all of them know what others capable or incapable of.
D’Artagnan asks Athos why he hasn’t mentioned the place where they could stay and tend to Porthos, just because he doesn’t really know yet that Athos never does or says anything if there is no point in doing so. D’Artagnan ponders if Porthos could actually kill someone (as a drunk mistake) and Aramis is instantly in his face, because d’Artagnan does not know yet how highly Porthos values his honour. (Because as you remember Porthos was talking about honour after they were all scolded by Treville in Ep. 2, but d’Artagnan was not there to hear it.)
Indeed, there is a talent that would certainly lead d’Artagnan to greatness. But it is years from now. And what we see right now is d’Artagnan genuinely asking questions because he is not yet 100% familiar with The Inseparables modus operandi. He is still learning.