Upon closer observation, I don't see it as tension so much as the sort of rivalry that builds up from working in close proximity over long periods of time. Hunters are the explorers, out there searching the dark places for lost relics and ruins. Warlocks are the scholars, delving into those same relics and ruins to discover their meaning, their significance...and possibly getting so lost in their work that they don't notice the angry wildlife behind them. Thus the Hunters acting as the eyes and ears for them. However, when they get to the door locked by some archaic, lost technology, then the Warlocks are there to provide the insight and knowledge to get the doors open, or to disarm the traps that wait beyond. The two need each other, but at the same time, that need is often because of shortcomings from either side. As such, they tend to smart-talk each other, but they'll always have each others backs in the end.