It's always about the slow burn, isn't it? The tension between Alvin and Jeanette in the fandom hinges on that core dynamic of 'rule-follower meets rule-breaker.' You see it in almost every story. It's never just about them getting together; it's about Jeanette learning to loosen up and Alvin discovering a reason to care about something other than his own schemes. Her meticulous planning contrasted with his chaotic, spur-of-the-moment energy creates a natural narrative push-pull.
A huge theme I keep running into is the idea of secrets and vulnerability. So many fics use Jeanette's quieter, more observant nature to explore what Alvin hides behind his bravado. The premise often starts with her noticing something's off—maybe he's quieter than usual, or he missed a prank opportunity—and that curiosity becomes the gateway. She becomes the only one who sees past the 'Alvin gets what Alvin wants' exterior, and he, in turn, starts trusting her with things he'd never tell Simon or Dave.
Then there's the 'unexpected protector' trope. Alvin, for all his selfishness, has a fiercely protective streak that writers love to aim at Jeanette. It might be against a bully, a bad situation, or even just Simon teasing her a bit too much. Seeing him shift from causing her trouble to defending her is a classic arc. It works because it feels like an extension of his loyalty to the brothers, just redirected in a surprising, softer direction.