I see we are once again ideologically opposed. Apollo's taking the burden of other people's suffering onto himself (to an unhealthy degree), while Achilles is apparently using his own suffering to fuel his wrath and encouraging others to do the same (to an unhealthy degree)

Apollo will remember who Achilles is, and may even recognize him as a centaur, but has forgotten so much about himself that he has forgotten what kind of relationship they've had pre-Abraxas.