[He's going through a few ideas - "Mordred was a druid!" "I tried to kill Morgana several times and almost succeeded!" "I hated your father!" "Your sword's story is bullshit!" "I once kissed Gwen!" and... a very specific one he doesn't want to reveal out of embarrassment rather than fear of how it'd affect you]
[.....]
I was the one who released the Great Dragon, that time. [He... can't quite recall if you know this already. He did tell you about his father, that much he knows, but...]