They are usually portrayed as the illogical version of Vulcans, They are cousins and they sometimes act closer to Klingons. This is not an attack on Klingons but lets face it they aren't known for their smarts but their fighting prowess. Except for Worf who was trained by SF to think more foreword. Vulcans chose to leave all that stuff behind that Romulans revel in. But they may see themselves as smarter than a Klingon and a human and a lot of that is partly arrogance because they usually see themselves as better than all races, once, outside of Vulcans before they became bitter towards them.