The Ancient Banyan Tree likely had developed a certain level of sentience, or perhaps, because of the long-time benefits it received from Qin Niu, it had come to consider him as a good friend. Helping Qin Niu become stronger allowed it to gain even more benefits.
Many plants and wild animals have this kind of symbiotic relationship.
For example, rhinoceroses rely on small birds to get rid of parasites on their bodies. Or the mongooses and drongos that utilize the drongos as sentinels.
Actually, when the drongo acts as a sentinel for the mongoose, it also expects a reward.
When the mongoose digs up insects from the ground, if it does not give any to the drongo, the bird will deliberately make an eagle's warning call, giving the mongoose a false alarm. The frightened mongoose will drop its food and flee back into its burrow.
Then, the drongo would eat the insects the mongoose just dug up.
