Pantheon & Aatrox

So, from Aatrox's lore we get this about Pantheon

...the newly reborn Aspect of War united many in fighting back against them (the darkin).

But Aatrox's quotes seem to hint at something a bit deeper than just that, at least from Aatrox's perspective, something more personal.

Hail Pantheon! Let me hear you cry of friendship! Let me hear you scream of brotherhood!

Hail Pantheon! How noble and proud he carries himself! Come betrayer! Come fiend!

'Betrayer' doesn't seem like something you would shout at a random aspect doing his duty and fighting against you. You wouldn't be happy, sure, but that seems like pretty specific language. That plus mentions of 'friendship' and 'brotherhood' has made me wonder... were Pantheon and Aatrox friends once? I could see them maybe getting along prior to Shurima's fall. Perhaps some circumstance pushed them together to where they had to fight back to back and they gained respect for one another in true warrior fashion. Though come to think of it I'm not sure I've heard of any of the Aspects and Ascended interacting prior to Shurima's fall so I'm unsure how plausible that is.

Another possibility is that Pantheon slipped into Aatrox's service much like Myisha/The Aspect of Twilight did to Ta'anari before betraying him. Though at that point I'm not sure how much 'friendship' could be had between Aatrox and someone he would perceive as mortal like Pantheon (assuming he perceived him as mortal since Ta'anari perceived Myisha as mortal).

Whatever the case may be I'm interested in whatever past they may have shared together and how deep this rivalry goes. I can only hope that we get more lore/details whenever Pantheon's inevitable VGU comes up.