One of the reasons Leslie is such an invaluable friend to Ron is that she protects him from his own worst instincts. And most of those instincts involve Ron's ex-wives, Tammy One and Tammy Two, who exert different but equally destructive types of power over him and who he keeps returning to romantically, against his better judgement. Whenever Ron is dragged into a relationship with one the awful women from his past, Leslie is there to bring him back to reality. Imagine having a friend who will do battle with your exes- and even break up with them- for you so you don't have to? What a (probably unhealthy but who cares) time saver! This commitment to Ron almost killed Leslie in an episode in which she challenged the Tammys (including Ron's mother, also called Tammy, don't think too hard about it) to a drinking contest and was forced to consume toxic hooch. Now that's commitment.