Athos and Aramis

Aramis and Athos are as different as day and night, as they have different views, especially while Aramis takes death seriously, Athos takes drinking seriously. Though they have many differences, Athos and Aramis are de-facto brothers and very close with one another. It is this friendship that causes Aramis to defend his best friend from anything, including a very enraged D'Artagnan when he thought Athos killed his father. Aramis immediately warned Athos of D'Artagnan's dagger and came to his best friend's aid and were willing to protect Athos from being taken into custody. Of course, Aramis decided to even go to D'Artagnan to save his friend of execution.

Of course, out of the four Musketeers, Athos is more familiar with Aramis' past romances, as Athos knew of Aramis' relationship with the Queen and how he enjoyed a romantic relationship with the mistress of the Cardinal's. Of course, Aramis' relationships tended to get in trouble, as Athos puts it, wishes Aramis wasn't "that stupid" in sleeping with married women but that was not the case. Athos still kept Aramis' secret relationship with Anne a secret away from their other friends until "The Accused".