To add onto this because since I have first seen this post my brain has latched onto the idea of it- and of a potential reveal of how much the first years love (platonically in this situation) each other.
It being shown through true love actually saving them-
Potentially they are visiting another school, or another school is visiting them. Mayhaps its RSA, but it could just be another magic school. Doesn't entirely matter, we just need a fresh set of students whereby the overblot curse follows Yuu (and to a smaller extent the first years).
One, or if you want to go for more angst two, of these new student overblot at the same time. Maybe they were the weird kid friends who had been pushed around too much and had to use magic to defend against an attack the others did, maybe they were rivals who had been arguing and had pushed things too far brining magic into it. Doesn't exactly matter. There just needs to be one, or two, overblot(s).
For fun reasons Im going with there being two overblots at once.
Now, the only people close to this at the time are as always, Yuu and the first years, the rest of the other schools students (oss) crowley and a teacher or two of this other school. Other NRC students would be about but these are the closest to the overblots.
When the overblots begin happen Crowley and the other schools teacher notice first. They're the oldest there and have either experience around oberblots, if brief, (Crowley) and know how the magic of their students behave (The other teacher). The teacher tries to push forwards, to go and try to help the overblotting students but some of the oss notice and point it out.
This then leads to the oss panicking. They run away, physically pushing all students (including NRC ones) away, maybe dragging some with them during their 'escape', preventing some of the overblot seasoned students (those who helped out and had overblotted) from helping as soon as they could. Crowley leaves to 'secure the perimeter' with the other teacher. Practically leaving the first years alone to fight two overblots.
For this im imagining the overblots to be based off of characters from Atlantis: The Lost Empire and Atlantis: Milo's return (some of my favourite movies). Specifically the Heart of Atlantis and the Spear of Destiny.
Fast forwarding a bit during the overblots.
After some undetermined but long period of time (because of how quick they typically are in game just imagine this fight taking longer than the overblot fights we've seen) the overblots are still fighting everyone.
The other schools teacher has manages to escape Crowley and returned to help the first years, and by now other NRC students (like the housewardens and vices), out.
The first years have been slightly sidelined to prevent them from overblotting due to overusage of magic. I'm picturing them kinda off to the side, away from them with Sebek and Jack closer to the overblot as they dont have as much blot accumulated + can fight the best, Ortho, Yuu and Ace in the back and Druce and Epel kinda in the middle with there being a literal wall behind them-
Kinda how im picturing it:
But then something goes wrong. As it always does.
Both overblots charge an attack aiming at those who are fighting them (in picture reference the big blue oval-like shape) however the other schools teacher is there and uses their unique magic (which im picturing acts similar to mirror force from Yu-Gi-Oh, "When an opponent's monster declares an attack: Destroy all your opponent's Attack Position monsters." ) preventing the attack from hitting them. But the overblots dodge a majority of it leaving it to instead hit the first years. Launching them into the wall and killing them.
However, because they were all together, seperated and injured one of them decided to jokingly and then not-so-jokingly say something along the lines of a "if I die here I want you all to know I love you" speech. Thus causes practically a bunch of confessions and allows the true love to grow stronger because they are recognising and admitting their feelings. The acknowledgement of their shared love for one another amplifies what true love can do for them.
But to everyone else, the attack hit something other than the overblots. And then either someone sees it and shouts, or Iida notices something about Ortho being damaged and announces it/shouts about it, but both ways attention of everyone, including for a moment the overblots, goes to where the attack landed.
But none of them can run over to check on them because the overblots turn back and continue the fight.
Nobody can leave to check on them so it continues but with grief hurting the the magic of the students and the other teacher. But, the grief also amplifies their determination to stop them.
Towards end, when they are nearly done fighting the overblots, a blue flame hits the one based off of the Spear of Destiny. This shocks everyone enough to turn towards where it originated from and there they see the first years.
Their clothing is battered and bloody but from what the ones with immaculate eyesight can see, it doesn't look like they are overly injured themselves. All together, with half aiming at one snd half the other, they send off a final attack and both overblots are gone together.
Omce this is done they fall down not from injury but from exhaustion. All of their respective Housewarden + Vices + others clamour to get to them and they notice that they are awake and practically injury free (im thinking that true love saved them from death + life threatening and bleeding injuries but left bruises and such bevause of how much was needed to save their lives).
They move them away from one another to check on them + transfer them to the infirmary (alongside the overblotted duo) but when they do the first years slowly, or quickly depending on who, fall unconscious.
In the infirmary they discuss what actually happened and they look over + discuss what they know + some textbooks and they come across True Love.
Reactions to the knowledge ensue.
Thats what I've thought of so far.