Events of Red Dead Redemption 2
Castor's Ridge begins as a camp around a fledgling farmhouse. In 1899, a father and his two sons can be seen building a house here, and Arthur can interact with them.
In the first one, the sons put up a wall on the front of the house and drop it, causing the father to berate them. He tells them to put it back up and then to back away before they make is worse. Cavis and his brother will go to their camp and lament their father's nagging.
In the second encounter, the camp comes under attack by a group of four extortionists, which Arthur can choose to fend off. If he does so, the father will thank him, and reveal that the men who attacked him and his sons did so because he refused to pay them protection money. He then returns to the house, where his sons are hiding, and asks them why they didn't shoot at the attackers, to which they claim that they don't have any guns.
In the third encounter, the father tells Arthur that they are nearly done building the house, but need some more supplies. Arthur can give him $100 or agree to deliver the supplies to him. If he chooses the latter, he must order supplies from the Appleseed Timber Company camp in Big Valley; the wagon of timber costs $75, and can be delivered to Castor's Ridge. Alternatively, a wagon can be stolen from the Appleseed Timber Company, from Valentine or from an NPC on the road driving one.
In the fourth and final encounter, the father informs Arthur that he sold it to a farmer who's moving south. If Arthur agreed to give him money, he will pay him back $100.
Soon after the final encounter the father and his sons are able to finish the house, and now there is a small fenced garden with vegetables in front. Arthur can encounter the farmer and his wife, who will ask him to leave if he stays in their house for too long. The couple can also be come across by John Marston in 1907.
During the second encounter, if you have already acquired a Volcanic Pistol, the father will possess a Volcanic Pistol that can be taken through disarming or killing him. However, this will end the Castor's Ridge encounters.