Stability
It was a well-known fact that the members of the so-called team Taka weren't particularly mentally stable. Karin was Bi-Polar, Juugo had split personality disorder, Sasuke had Uchiha Complex (as Naruto had dubbed it) and Suigetsu had an unhealthy obsession with tearing things apart.
So it was with great surprise that Suigetsu discovered that he was actually the most 'normal' ('closest to sanity' was how most phrased it). Unhealthy obsession with tearing things apart aside, he proved the most capable of integration into Konoha society after the war.
His sense of humour had led to him making friends with Kiba and Sai (the former would often drag him off as a drinking buddy), which had led to making friends with other social drinkers in Konoha.
But as be watched Kiba flirt hopelessly with some of the other regulars and Ino leaned against the bar beside him, rabbiting on about how she never really like Sasuke, she just acted like it 'cause everyone liked Sasuke and - Hey, your teeth are kinda cute, Suigetsu! He couldn't help but wonder if team Taka wasn't the only people he was saner than.
Or maybe he just had better alcohol tolerance.