What exactly was the motivation towards the formation of the Typhon Pact? It's been a while since I read ASD... I know it was stated that the president outbid the Tholians (or something like that) in hiring the aid of the Orion Syndicate for protection against the Borg, but I'm not sure how this inconsequential and seemingly little event should tip the scales far enough for a whole multitude of races to form what seems like it should be an extremely unstable alliance. As is stated, most of these races are extremely xenophobic, so why are they working together?
You might as well ask the same thing about the primary member states of the European Union. Britain, Germany, and France all have long
histories of aggression, xenophobia, ethnocentrism, racism, imperialism, and dictatorship, and goodness knows they've all gone to war with one-another dozens of times over.
And yet the European Union exists and doesn't look like it's going anywhere any time soon.