Its about how you play your character, and very much your choice. Like for example, Brigante here is not racist against Darkspear Trolls, they have never been enemies of Quel’thalas (That was the Amani) and have only ever been allies, he respected, still does, Vol’jin.
However, He fought on the Isle of Thunder, he remembers warring with the Zandalari, and whilst he may grudgingly accept them into the Horde as comrades, he -is- going to have issues with them.
So really, it doesn’t matter what -you as the player- have done, it matters what -you want your character- to have done. Like, I obviously played through Argus, but did Brigante the character go to Argus? Heck no.
Don’t feel you have to tie your character into what you quest through. for example, Brigante (A Dragonhawk rider) was not doing much during Vanilla, few aerial patrols to keep the Amani in check. During TBC he was enlisted in the Shattered Sun Offensive, but that part on Azeroth, he never actually went to Outlands at the time (Obviously I did whilst questing, but the character didn’t) during WotLK he was pretty much one of the Dragonhawk riders in Icecrown, tussling with the frostwyrms. During Cata a lot more border patrols against Amani and praying that Deathwing didn’t come into the Skies, During MoP more of the same, was eventually sent there as the conflict heated up and later took part in the Darkspear Rebellion.
See what I mean, you can kind of write your own backstory using world events as the backdrop, the scenery, but you don’t have to pretend your character did the things you did. Brigante didn’t kill the Lich King with 24 other people. He never even -saw- the Lich King, apart from distantly, from like five hundred feet in the sky, for a second or two.
He neve killed Kael’thas, nor Deathwing, Kil’jaeden or Gul’dan. He was -involved- in all of those wars, sure, but he didn’t do what I as a player have done.
Just don’t claim to be the mighty person who struck the final blow on Arthas for example, and you’re good.