It appears Locke's father arranged the meeting between Locke's mother and Locke, knowing that it would lead to Locke tracking him down. He then forms a bond with his son, spending time with him, teaching him to hunt, etc. After some time, he reveals that his kidney is failing and he needs a transplant. Locke decides to donate his kidney to his father. But, when he awakes from surgery, he finds his father is gone and that he has cut of their relationship. Apparently, the whole set of events surrounding this timeframe was just a ploy by the father to get a kidney for himself from his son, whom he really cares not to have a relationship with.
