You would pass it down from one generation to the next as long as the next generation pledged fealty to their lord. The title knight, however, was given for service and did not tend to be passed down from generation to generation, and to be clear, these still aren't all the actors here. You also have the church, which during medieval times was a very powerful institution. At the top of the church, you had the Bishop of Rome, also known as the pope, and you had their bishops in significant regions. You also had monastic orders, where you might have an abbot who is the head of a monastery, where you have monks who, as part of that monastery, are praying, they might be farming, they might be copying texts, and there was also power dynamics between these, and as we're about to see, you can even have these non-religious figures pledging fealty to religious figures. So just to get a sense of what these pledges of fealty were like, you have a vassal in this homage ceremony, homage, or sometimes said homage, and it really comes from the French word homme, which refers to man, so he is pledging to be his lord's man. So this would be the lord right over here, and this is an actual pledge given by Bernard Aton, Viscount of Carcassonne, in the year 1110 in France.