When you do something generous for another person, they feel compelled to reciprocate. Not alway, but often.

They will also feel more generous towards others.
Not always, but often.

This has been established through research, and it links to the idea that we are essentially altruistic.

We like to be kind and generous to others, and this sets up a ripple effect, in a kind of web of kindness.

Not always, but often.