What happens when all you do is ask from a relationship without giving anything back? The other party won't feel there is any value in continuing to interact with you.

What happens if all someone does in a relationship is 'give' to you without taking anything you offer them? You won't feel you are contributing to the relationship, you won't feel valued for what you bring to the relationship, and the interaction will be discontinued.

A relationship is an ongoing interaction in which parties perceive there is more value in participating, than not. To strengthen and grow relationships, parties engage in a two-way flow of values-exchange through ongoing 'give' and 'take.'

Most people think that it is more important to 'give' than take in a relationship. Yes, having a ‘pay it forward’ culture is one of the things that makes Silicon Valley (SV) a special ecosystem. However, it's just as important to 'take' as it is to 'give' too— it must be balanced. Therefore, in continuing to grow and build a relationship with anyone, get clear about the following:

How you can be of benefit and service to them— what do you want to give or do for them?
How can they be of benefit and service to you— what do you want them to give or do for you?

To better understand how each party can stand to gain from one another, you must do your research:

Understand their operating context, including goals/aspirations, challenges, pain points. When you appreciate their operating context, you can clarify opportunities to add value to their lives. You might not always have access to detailed information about this, and you will often have to make rational deductions. The point is to be thoughtful.
Elicit their value systems. People's behaviors demonstrate their core values. They always have time and resources to dedicate to their highest values, while they often never find the time or bandwidth to dedicate to their lowest values. By doing this, you can identify ways to help them fulfill their highest values.

Remember: if you are doing a favor for others, you must also remember to ask for one back. It doesn’t have to match the monetary value or significance. It simply has to be a meaningful reciprocation that serves to continue the flow of ‘give’ and ‘take.’