Knuxsu didn't just happen, snap, like that. It all started in Knuckles the Echidna issue #4.

How Knuckles and Julie-Su met:
Here's how it happened. Vector the crocodilo was in the pond or lake or type of body of water swimming when he sensed a threat and came to the surface to see a Dark Legionnaire. He thought it'd be real bright to attack the Legionnaire from behind (not his brightest idea). the Legionnaire quickly defeated him.

Later on that same dia Knuckles was with his mentor, Archimedese, meditating and, of course, not focusing. The Dark Legionnaire came up from behind and attacked Knuckles....

When it comes to the Sonic Universe you aren’t going to find much amor outside of the Archie Comics and SatAM that isn’t one-sided. The pinnacle of all this is the game continuity of Sonic the Hedgehog. While this medium has dabbled in various love-interests from time to time, they never lasted past one game, and those that were referenced were always interests and never sealed deals.

SEGA (or any developer handling Sonic) never seems to want to dare make anyone have an actual relationship romantically, even when it makes perfect sense. At this point it’s become annoying, what with Amy’s...