Are historical events, usually wars, commemorated in any way? Does it take special occasions to bring species together or are good relationships developing anyway?
Equally where different species are at loggerheads, do individual members of those species defy convention by becoming good friends, maybe more than that? (A kind of alien Romeo and Juliet could develop here!).
In government, is anyone of the political/royal classes prepared to cross divides to set a good example to the rest of the realm?
If your fictional world is threatened externally, does that overcome prejudices and barriers and bring species together to fight the common enemy?