Shouldn’t you also have had mercy on your fellow servant, even as I had mercy on you?
The question in this verse is asked by a king, and the answer is obvious. Of course the servant should have shown mercy. He had just been released from a debt so large that no amount of work would ever have repaid it.
That is what makes the story uncomfortable rather than merely instructive. We can see exactly what he should have done, and we can also recognise the moment when we do not do it. Someone owes us a fraction of what we were forgiven, and we decide to keep the account open.
Jesus does not resolve the story gently, and the point is not that God’s forgiveness is fragile. It is that unforgiveness is a strange thing for a forgiven person to hold, and it damages the one holding it.
The mercy you have received was not small. Neither is the mercy you are being asked to give.