In the Water Margin, the first friend Lu made was Shi Jin. At that time, Shi Jin met Lu in a teahouse. He was looking for his teacher. Lu always likes to make friends with Jianghu heroes. Seeing that Shi Jin was tall and burly like a tough guy, he immediately stepped forward to greet him. Later, I learned that this man was a famous nine dragons in the Jianghu, so I invited him to drink. From Lu's performance, we know that his criteria for making friends are: first, to be a hero; Second, have a good reputation.

They met another man in the street, Shi Jin's master, but he didn't look like a hero, but because he was Shi Jin's master, Lu thought he should be not bad either, so he invited him to have a drink together, but he didn't expect to be secular and wouldn't close the stall when he saw many guests. He also dawdled for a while, and only after selling some ointment would he go with him when he rescued Jin Cuilian's father and daughter.

Reluctantly took out two taels of silver. Lu saw that this man was stingy and disdained him, so he was not counted in the circle of friends. Therefore, the second criterion of making friends with Lu is generosity. When he fled to Taohua Mountain, he saw that Jong Li and Zhou Tong didn't want to use a lot of gold and silver in the cottage, so they had to rob him to see him off. Knowing that they were both stingy, they left without saying goodbye.

Lu is a martial arts practitioner and advocates martial arts. Therefore, when he saw Lin Chong's extraordinary skill, he immediately became sworn brothers with Lin Chong. Later, he met Song Wu and they became inseparable friends. This is also the reason. As for Lu's association with a gang of gangsters while guarding the vegetable garden, it's just a boring time to kill time. They are not in the same class as Lu, so they are not Lu's real friends.