I've been thinking about how Ranma falls for Akane. It's definitely her smile, but it's also everything about the way she approaches him: friendly and considerate, taking him away from an uncomfortable situation. From their first interaction, it already says she's on his side
Virtually every character Ranma meets challenges him to a fight. The way it goes down communicates a lot, so it stands out that only Akane's offer is friendly. It's not a challenge, revenge, hostility, or competition. This is Akane offering to connect through the thing she knows they have in common.
Nobody approaches Ranma like Akane does: with friendliness, consideration, and a no stakes competitivity. The fight is our first glimpse at Ranma's insane skill level, and Akane is the only one who reacts to a loss with a laugh, because with them fighting is connection
By offering this connection, Akane is essentially welcoming Ranma to her house and her life. Their fight also foreshadows part of their dynamic: their fights are a form of communication. No one riles Akane up like Ranma. He'll always go after her (the fight literally ends with him behind her, reaching out to touch her).
This is a comedic scene but I think there's something about them both being so exposed on their first meeting. They have nothing to hide from each other – literally (iirc Ranma is always covered at least by water from the waist down, but Akane is seeing everything lol)
Speaking of exposure: they practically show their worst, least palatable sides to each other right from the start... and they're still not repelled (like they are when their other suitors show them their worst).
Also interesting to compare Ranma's first fights with their other suitors to the one with Akane. They're unserious clownery: Ranma kicks them (misunderstanding or attempts at de-escalation). But he only poinks at Akane with a finger. It's soft, tender, and reinforces connection.
Right from the start, Ranma cares about not being rejected by Akane. When she does, it doesn't have any weight: it's not that she really hates boys, she's just tired of being harassed (we get the reveal that every morning she has to fight the boys in her school – who try to beat her to date her – pretty much in the next chapter). "We're not friends," she might say, but she immediately confides in him and essentially lets him look at her heart.
Everything about the way they fight from the start is established with an undertone of connection, a pig tail-pulling sort of camaraderie. Through their fights, we see how similar they are. When the fight is with an outsider, they work as a team. It's them against the circus.
When her smile makes his heart speed up (distracting him so much he doesn't see the ball coming) he's already jealous and worried about his feelings being unrequited. The hints of Akane being/becoming his best friend and supporter have already been laid by the time her beauty is highlighted.
Akane grabbing Ranma by the pigtail is a constant throughout the manga. It's hilarious, but also: only she is allowed to do this... And the fact that it happens in the first couple of chapters highlights how quickly Ranma connects with her/trusts her
annaxmalina
dededos
stormborns
