I'm going to make what I assume is an unoriginal observation, but it came to me in contemplating fairness in the context of libertarianism. Feel free to point out why my thinking here is completely wrong.
It's my understanding that the fundamental principle of Libertarianism is that it is wrong to initiate force. If force is used against me, I can respond with force, but when no force is used against me, I may not. A second tenet is that fraud is wrong - I should not attempt to gain by deceit. But Libertarians also have this idea of "property", and this is where I think the philosophy goes off into the weeds.
Let us stick to the first principle for now. Initiating force is wrong. If that is so, then consider the following situation. I have a house. Someone picks the lock on my front door and moves into my spare room. Finding a key to the house, they make a copy of it, returning the key, and continue to occupy my house. They stay out of my way, and act like a good guest, providing their own food and so on, but it remains that I did not invite them. And so I undertake to evict them, by forcibly removing them, and by standing guard so that they can't come back to the house.
Who in this case initiated force? Was it the person who moved in to my house? Or was it me, when I tried to evict that person?
I think that you could make a case for either position. And I think that if you take the latter position, you are right, and if you take the former position, you are fair.
I don't mean to propose that we should all accept it when people break into our homes and move into our spare bedrooms. What I mean is that if you take this as your premise for how Libertarianism works as a philosophy, then you wind up with a society in which the common good is cared for. And if you take the other position, that it is okay for me to use force to evict a squatter, then you wind up with a society in which the common good is not cared for.