I Was Foolish & Wild, She Was Classic & Regal

When it comes time to give James the talk, Harry realises that explaining the birds and the bees isn't going to be enough to drum the message into his stubborn son. So he tells him a story instead, a story about a girl Harry knew a long time ago, and a close call they had almost had...

[Had this in a multi-chap, which I deleted and decided to re-upload as stand-alone ficlets]