Conversation according to most dictionaries is the spoken exchange of thoughts, opinions, and feelings
How fun is it when someone tells you how much they have just enjoyed a conversation with you and you smile to yourself. In the two hours that the two of you were seated across from one another, the only thing you can remember doing is nodding your head. The few times that you were able to speak a few words reminded the person across from you of an event in their life which took at least twenty minutes to tell.
You can't be angry at this person because it's just not with you that this happens. You have seen them react with others in the exact same way. Perhaps they think their life is so much more interesting than yours, perhaps they are lonely and this is their way of being with someone. Maybe they never got the chance to actually learn how to exchange ideas because no one ever took them to task for this behavior.
Sometimes it's frustrating and then sometimes you just have to accept this is the way the person is and if you have a relationship with this person, this is the way it is going to be. You are hoping it is just a personality quirk and that they are possibly not that narcissistic. How sad would that be.
Of course my favorite things is to get the first drop, start a story and every time they want to interrupt, just talk over them. I did this to someone who was always talking about them and their life and I heard from my friends that this person could not believe what a big ego I had. I still laugh when I think about it.
Moral of the story is to remember a conversation is so much more pleasant when all parties involved get to finish a thought, idea or just a fun story without the having to one up, interrupt or just talk over them. Try it and all of a sudden everyone enjoys talking to you.