Should you actually want a conversation, I would suggest the following topics of conversation:
Whether Draco/Hermione works better than Draco/Ginny, and why not.
Which authors will make you buy a new book of theirs immediately even if you had no idea there was a new one out.
Your most embarassing drunkeness story.
And name one film everyone should see at least once in their life.
Happy now, your Imperial Highness?