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 krokodil was in the pond of lake of 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 dag Knuckles was with his mentor, Archimedese, meditating and, of course, not focusing. The Dark...