You know, I only just remembered as I was thinking about this question, that it had actually been inspired by another story, one that I can remember reading, but not where, or what its title is. But it had a similar scenario: Tim and Kon were together and Bruce and Clark were wondering if they should tell them about their own failed relationship. So the scene that Dick, Tim and Kon witness on the watchtower was what really started the fic off, along with some of Kal's dialogue - the 'Never' line, when Bruce tells him to let him go - as well as a desire for a happy ending, with Dick, Tim and Kon, with Alfred's help, having got Bruce and Clark back together.