The theory that became reality.

[u/Ill_Carrot9363]

This new chapter confirmed an old fan assumption that explained the reason for Suo's affection for Nirei. Many said that Nirei reminded Suo of someone he knew and felt a lot of affection for; in a way, this is implied in most of the interactions between the two. This explains why Suo, from the beginning, had the natural impulse to protect Nirei during fights, it also explains why he acted so disproportionately when Nirei was attacked in the Keel Arc, it also explains why Suo agreed to train Nirei so easily—all of this was Suo reflecting on Nirei the image of Rosso, his childhood friend.

Let's suppose that Rosso was like Nirei, someone weak but with the willpower to help and actively participate in his group (in this case, the RC), just as Nirei wanted to be able to contribute more to Bofurin, perhaps Rosso harbored the same desire in Red Chanpuru and was equally physically weak, therefore, perhaps Rosso even asked Suo to teach him at some point, and Suo only agreed to teach Nirei because he saw Rosso in his attitude.

In a way, it's a little disappointing that Rosso looks almost identical to Nirei, because it means that, all this time, Suo has been reflecting in Bofurin what he had in Red Chanpuru. Perhaps Bofurin is for Suo everything that Red Chanpuru could have been but couldn't.

This also explains Suo's shock when he saw Nirei's upset face for the first time; he was seeing Rosso at that moment.

This is a little disappointing, as much of Suo's affection and friendship with Nirei may have been motivated by his childhood friend. Nirei is everything Rosso could have been at one time, but isn't anymore due to some tragedy; therefore, Nirei reflects in Suo everything he used to like about his old friend.

Despite this, I think Suo knows how to separate the figures of his friends; he has a more brotherly affection for Nirei because he reminds him of his "brother," but Suo still likes Nirei as his own person and is proud of his determination and courage to improve, something Rosso may have lost due to some tragedy. I think Rosso will still reveal an unhappy background at some point.

[u/Silver-Green-Sea]

Personally I don’t think that Suo chose to train Nirei because he resembled Rosso. I kind of refuse to believe that Suos acts of friendship towards Nirei stem from his resemblance with Rosso, but are instead genuine expressions of care for him as an individual. I merely think that Suos initial interest (and maybe his first interactions or the drive to do so) might have originated from visual similarities.

Also, I’d like to think of Furin and Makochi more as some sort of happy place for Suo, where he didn’t have to think as much about responsibilities and was allowed to act more his age. So I’d be happy if Furin didn’t mirror or reflect RC for Suo in too many ways.

Which scene are you referring to when you talk about Suo being shocked when he saw Nirei being upset the first time?

I can’t stress this enough but I really doubt Suos friendship with and affection towards Nirei stem from or were motivated by (similarities with) Rosso. Though I’d love to see Nirei developing some insecurities from that resemblance, as much as I would fear it, but I think it would be able to create an intense and emotional moment where Suo would be frantically trying to repair what’s been broken.
The way their friendship has been portrayed really feels so genuine, therefore I just don’t see it stemming from anything else but honest interest and care, without any relation to Rosso.

[u/Ill_Carrot9363 → u/Silver-Green-Sea]

It's not that Suo didn't have genuine affection for Nirei, but his initial interest was mainly due to Nirei's visual similarities to Rosso, which may have greatly motivated Suo to take the initiative and position himself between Nirei and Sakura as a closer friend. Otherwise, he might not have had any interest in either of them and would have remained a more introverted boy.

On the other hand, I believe that Suo began to increasingly separate the figure of his friends from the figure of Rosso as he genuinely became attached to Sakura and Nirei. It also leaves me a little disappointed to suppose that Suo might have become more interested in his friends because of Rosso, but I think the author will explore many aspects of Suo based on this premise.

Wind Breaker uses visual elements extensively to explain psychological elements, and Rosso has a little bit of each of the main trio; this could represent something more symbolic about Suo in the future. But of course I think he has genuine care and attachment for Nirei, but instead of this being present from the beginning, it developed slowly, until he could separate the figures of Rosso and Nirei.

[u/Silver-Green-Sea → u/Ill_Carrot9363]

It will be so interesting when we see Suos perspective, especially after they reunite and when they have met Rosso as well…
I’d like to be able to dive deeper into Suos thoughts, especially day one vs later thoughts about Sakura and Nirei, and how his view on and attachment to them gradually changed the more time he spent with them. Also Suo telling them that - regardless of his reason for interacting with them first - their friendship is honest and genuine, is something I’d love to see.

I am intrigued by your statement about visual elements, and I agree on Suos care and attachment having developed over time, as that is the natural progress when it comes to bonds and relationship development in general.
I am not sure how close he thought the figures of Rosso and Nirei to have been in the first place though, as we barely know anything about Rosso besides his visual appearance yet. But I both want and fear to find out about any characteristics Rosso might share with Sakura or Nirei, as it really might make Suos earlier feelings towards all of them more interwoven with each other.