Maybe he should have asked you what qualities do you think another person should present to you to gain your trust in them? If you could think up what a good friend would be like, what qualities would you put in that person if you could?

For myself, one quality I would like is honesty, also that the person would respect what I like because it makes me happy rather than expecting me to like what they like or think is important. I also appreciate it when another person respects my feelings, allows me to feel if I need to (ofcourse within reason). Also not treat me badly if I don't happen to know something as well. People make mistakes all the time, I like them to be honest about a mistake, I may get angry as that is normal depending on the mistake, but if the person is honest with me I am very forgiving, when they lie it makes the mistake even bigger IMHO. I think listening is important too, if a person listens to me and shows me they are and is respectful, that builds my trust in them too.