Think about this statement:
In any relationship, the person who cares the least, has the most power.
In most relationships, power is an issue, especially with some people who depend on power to boost egos or reign over other people.
Do you really understand the statement above? If not, I'll try to explain it succinctly.
Two people in a room, say a dorm room. An agreement made before the union states that one person will do the dishes, the other will pick up trash and empty it into the dumpster.
The person who does dishes, is diligent and every day, walks around the small apartment, picks up all the dirty dishes and then washes, dries and puts them all away. The other person appears lazy and often waits 2-3 days before picking up the trash.
Dishwasher becomes angry at Trasher and one day yells at Trasher that his job is to pick up trash and he is trusted to do so in a timely manner. Later in the day, Dishwasher renews his anger at Trasher and yells some more as he walks around picking up the trash. He yells that this is the last time Dishwasher will do Trasher's job.
Think about this scenario for a minute. Go back up and re read it, if you'd like to. ... ... ...
Okay, here it is. Trasher holds most of the power over Dishwasher. Dishwasher doesn't like it, and he continually tries to exert power over Trasher to get him to do the job he promised to do. Trasher cares the least about a clean apartment, so he doesn't mind the trash laying all over. When Dishwasher yells, Trasher doesn't care enough to pick up the trash. His apparent laziness is not lazy, it is his disinterest in the situation, which to Dishwasher is a big deal.
The big deal to Dishwasher shows he cares more about a [not having a] trashy apartment. So - the person who cares the least will have enough power over the other to spur the other into action and he will eventually clean the apartment himself. Trasher will be able to force Dishwasher into cleaning the apartment and he doesn't have to do anything, except not care.