Spoiler Warning: This article contains major spoilers for Four Hands, Two Sonatas Episode 4.
Why is Kang Pi-o suddenly so threatened by Choi Jeong-yo in Four Hands, Two Sonatas?
The simple answer is jealousy.
But Episode 4 suggests something much deeper.
Pi-o is not just afraid that Jeong-yo might become a better pianist. Jeong-yo receives the one thing Pi-o has spent much of his life chasing: recognition from his grandfather, Kang Seung-woon.
That is what makes their growing rivalry so painful.
Jeong-yo is not a stranger Pi-o wants to defeat. He is the friend who helped Pi-o rediscover the joy of music — and at the same time, the person who exposes everything Pi-o fears he may be missing as a musician.
Why Does Pi-o Want His Grandfather’s Approval?
To understand Pi-o’s jealousy, we first have to understand what his grandfather means to him.
Pi-o has grown up in a world built around elite musical training, competitions and expectations.
He knows how to practice.
He knows how to perform.
And he knows how to compete.
But beneath all of that is a much more personal desire.
Pi-o wants Kang Seung-woon to recognize him as a musician.
His grandfather is not simply another family member whose praise would make him happy. He represents the musical authority Pi-o desperately wants to impress.
That helps explain why Jeong-yo’s arrival changes everything.
Pi-o has spent years trying to earn that recognition.
Jeong-yo seems capable of attracting it simply by playing.
Why Does Grandpa Choose Jeong-yo?
Episode 4 makes the contrast between the two young pianists increasingly clear.
Pi-o has been shaped by formal training and competition.
Jeong-yo approaches music differently.
He improvises. He experiments with harmony. He changes what he plays according to what he feels instead of always remaining confined by the score.
As Pi-o spends more time practicing with him, he begins noticing this difference himself.
He discovers Jeong-yo’s composition notebook.
He sees their teacher, Do Hyun-soo, react to Jeong-yo’s improvisation.
Even Hong Jae-in becomes absorbed in Jeong-yo’s playing.
Then comes the moment Pi-o fears most.
Jeong-yo plays in front of Kang Seung-woon.
His grandfather likes what he hears enough to consider performing with Jeong-yo.
For Pi-o, this is not merely another musician receiving praise.
It is Jeong-yo receiving the approval Pi-o wanted for himself.
Pi-o vs Jeong-yo: Calculation vs Instinct
This is where the musical conflict at the center of Four Hands, Two Sonatas becomes much more interesting than a simple question of who is the better pianist.
Pi-o represents control.
Jeong-yo represents instinct.
Pi-o has learned to succeed inside the system: training, technique, competitions and disciplined preparation.
Jeong-yo possesses a more spontaneous relationship with music.
This does not mean Pi-o has no talent or that Jeong-yo does not work hard.
The drama is asking a more uncomfortable question:
What happens when someone who has spent his entire life perfecting music meets someone who seems to understand it naturally?
For Pi-o, Jeong-yo becomes a mirror.
And Pi-o does not necessarily like what that mirror shows him.
Why Their Friendship Makes the Jealousy More Painful
There is another reason Pi-o’s reaction feels so tragic.
Jeong-yo was becoming his closest musical friend.
When Jeong-yo struggled with stage fright, Pi-o helped him return to the piano.
When Jeong-yo was in danger, Pi-o helped him.
And after their conflicts, it was Pi-o who suggested that they become practice partners because he wanted to discover how to enjoy music again.
That detail matters.
Jeong-yo is not only Pi-o’s rival.
He is also the person who reminded Pi-o that playing the piano could make him happy.
That creates a cruel contradiction.
The person who helps Pi-o rediscover his love of music is also the person who awakens his deepest insecurity.
Why Does Pi-o Become Jealous of Jeong-yo?
Pi-o’s jealousy builds gradually rather than appearing from nowhere.
He sees Jeong-yo’s natural musical sense.
He notices other musicians reacting to it.
He hears that people in the industry may prefer Jeong-yo.
He watches Jae-in become fascinated by Jeong-yo’s playing.
And finally, he sees his own grandfather recognize Jeong-yo.
Each moment reinforces the same fear:
What if everything Pi-o worked for can be surpassed by something Jeong-yo simply possesses naturally?
That is why calling Pi-o merely “jealous” misses the point.
His jealousy is connected to identity.
If being an exceptional pianist has defined Pi-o for most of his life, Jeong-yo’s talent threatens more than his position in a competition.
It threatens Pi-o’s understanding of who he is.
What Does Grandpa’s Warning to Pi-o Really Mean?
After Kang Seung-woon shows interest in performing with Jeong-yo, Pi-o finally confronts his grandfather.
He wants to know why Jeong-yo was chosen.
The answer is devastating because it attacks the insecurity Pi-o has already begun developing.
His grandfather essentially warns him that if this relationship continues as a competition, Pi-o may be the one who ends up emotionally destroyed.
The warning can be interpreted in two ways.
On the surface, Kang Seung-woon may simply believe Jeong-yo possesses greater natural musical talent.
But there is another possibility.
He may understand Pi-o better than Pi-o realizes.
Jeong-yo does not appear to define himself by defeating Pi-o.
Pi-o, however, is beginning to measure his own worth against Jeong-yo.
That makes the rivalry far more dangerous for Pi-o.
The greatest threat may not be losing to Jeong-yo.
It may be becoming so obsessed with beating him that Pi-o loses the happiness he had only just rediscovered.
Is Pi-o Really Angry at Jeong-yo?
This may be the most important question after Episode 4.
Pi-o appears angry at Jeong-yo.
But much of that anger may actually be directed at himself.
Jeong-yo did not steal his grandfather.
He did not deliberately take Pi-o’s opportunities.
And he did not become Pi-o’s friend in order to defeat him.
Instead, Jeong-yo unintentionally reveals Pi-o’s deepest wound.
Pi-o has spent years doing what everyone expected from him, yet he still cannot obtain the recognition he wants most.
That is why his jealousy feels less like hatred and more like fear.
Talent vs Hard Work May Not Be the Real Question
It would be easy to interpret Four Hands, Two Sonatas as another “talent versus hard work” story.
But the drama appears to be building toward something more complicated.
Pi-o has what Jeong-yo lacks.
Jeong-yo has what Pi-o lacks.
Pi-o gives Jeong-yo structure and discipline.
Jeong-yo shows Pi-o freedom and musical instinct.
When they play together, those differences complement each other.
When they begin comparing themselves, those same differences become weapons.
That may be the real meaning of the title Four Hands, Two Sonatas.
Two musicians do not necessarily have to become identical to create something extraordinary together.
The tragedy begins when one decides he must become better than the other.
What Happens Next to Pi-o and Jeong-yo?
Episode 4 appears to mark an important turning point.
Until now, Pi-o and Jeong-yo have repeatedly rescued each other.
Now talent, family expectations, money and the adults surrounding them are beginning to turn friendship into competition.
The most interesting question going forward is therefore not simply:
Who is the better pianist?
It is:
Can Pi-o accept Jeong-yo’s talent without believing that it makes his own music worthless?
If he cannot, his grandfather’s warning may become a self-fulfilling prophecy.
And that would make Pi-o and Jeong-yo’s relationship one of the most painful parts of Four Hands, Two Sonatas.
Related Four Hands, Two Sonatas Guide
Want a deeper look at the drama’s central themes?
Read our Four Hands, Two Sonatas Explained: Talent vs Hard Work, Rivalry and the Meaning of the Piano guide for more on Pi-o and Jeong-yo’s contrasting approaches to music.