I’m definitely gonna win!
You mean I’m gonna win!
You’re not gonna beat me!
I was going to keep my thoughts in the tags, but then I changed my mind because it felt too significant to not say.
This right here? It’s such a great inclusion, and people don’t think about its significance enough (or at least I haven’t seen anyone discussing it). A parallel is being drawn here, between Rin and Haruka’s needling banter and the children’s boisterous competition, and it’s being drawn, in-text, by Rin and Haruka themselves.
There are two extraordinary things about this. That Rin and Haruka, simultaneously, recognise themselves in the children running ahead of them, indicates just how much their relationship has changed and grown since the first episode of the first season. Eternal Summer’s first episode made many callbacks and references to the first season, and this is one of them: the mutual recognition and ensuing “aww” moment (for lack of a better term) demonstrate a level of consciousness and understanding of their relationship and each other that they most definitely did not have at the start of last season.
Before the glorious disaster that was their miscommunication got resolved, Rin and Haruka in the first season severely misunderstood each other and the nature of the other’s side of the relationship, in ways too complex to try to explain in detail here. In short, we got:
Rin, wrongly assuming Haruka’s complete indifference to him (evinced by the utter incongruity of his statement with the sudden change we saw in Haruka in the span of a single episode) and failing to see exactly how much he meant to Haruka until Rei went to Samezuka, and finally got Haruka to buck up and speak honestly,
and Haruka, plainly refusing to deal with how he felt about Rin and choosing to shut off instead, until he lost Rin twice more and could no longer ignore what he truly felt and wanted.
But then! Their banter at the beginning of this scene already shows the difference, the newfound understanding, when Haruka responds with what is essentially “you won’t beat me that easily” and Rin recognises mutual excitement for what it is - and then the kids come along and they simultaneously see themselves there, and it’s no longer telling just of conscious recognition of the fact that they both spur each other on competitively or the knowledge that the other knows too, it’s also indicative of how both now associate happiness with this state of relations (rather than angst, like in S1). Why else would an echo, an evocation of themselves, cause sappy smiles like that?
Character and relationship growth aside, this scene also pretty plainly spells out the fundamentals of Rin and Haruka’s relationship. It’s not so easy to see when it’s just Haruka’s quiet, tsun self versus Rin’s intentionally provocative nudging, but juxtaposed against and paralleled with the children’s thoughtlessly brazen, simple, naive energy, that they excite and spurr each other on positively and without guile, becomes plain as day. People try to make Rin and Haruka’s relationship out to be complicated and angsty and dark, and it is true that for a period in canon they could easily have become the worst most hurtful people to each other, but let’s not ignore that most fundamentally Rin and Haruka thrill each other, and in possibly the simplest way just want to be together, and that makes them both happy. You don’t even have to see this romantically at all (though of course it is so easy to read it as such when you take everything else into account…), it’s as simple as “he’s excited and so he’s going to be there to race him”, gosh. And if they happen to help each other become better, healthier, stronger people in the process, end up saving themselves and each other*? Well, that’s just - cake on top of the cake, more patty and veg for your burger, and all that.
*CREDIT TO REI OF COURSE credit to rei