There have been many "relationships" on Trek from Kirk and Spock, To Geordi and Data, To Sisko and Dax ( at least Curzon and Jadzia) Tom and Harry. I never really got a chance to watch much of Enterprise so I can't comment on that series, one relationship if you could call it that was the one between Damar and Weyoun, not really friends, not really enemies. Just two people thrown into a situation, I for one really enjoyed seeing them go back and forth about everything from military tactics, to Damars fondness for Kanar, what about you...
Resistance is Futile
Resistance is Futile