Note: In this part... I decided to cut off a bit "earlier", since the two versions I'm reading narrate things in a slightly different order and slightly different way. I mean, I know I don't have to follow the textbook at this point, but the next scene is more or less in a different setting already (although I will still actually read it before making the next summary and all), so I believe this would still be good.
Upon hearing of the punishment that is going to be given to his brothers, Don Juan goes to his father, the king, to ask him to forgive them. The prince reasons that:
Because of this, the king decides to forgive the brothers and not go through with the punishment. However, he tasks the three princes to keep watch over the Adarna bird and prevent it from flying away. And this is where things go wrong... again.
So, even after he and Don Diego were already forgiven (when they could not have been. After all, the king was still the king and also their father, and he could have chosen not to give Don Juan what he asked for), Don Pedro was still giving in to his feelings of envy regarding his youngest brother. And what they decided to do was to go together for a shift, then have Don Juan go at it alone.
They wake Don Juan up one midnight (possibly while he was sleeping on the expectation that it would be his turn much later, I don't really know), and so he was the one who was on duty from midnight onward. However, he couldn't help but fall asleep around early morning.
While he was sound asleep, Don Pedro goes to the cage carefully, then opens it, leaving the bird to go off on its own. Then he walks away without saying a word.
Don Juan wakes up around morning, and finds the cage empty. He then becomes scared of what will happen when his father finds out (from what I understand, it's possible that someone might be put to death, if ever), and so he leaves the castle. (in the textbook I'm reading, it elaborates on this by saying that Don Juan left so that no one gets punished or something)
After this, the narrator goes to the king's side of things.
When the king awakes, he goes to the bird cage, and sees it open and without the bird inside. Because of this, he calls for his three sons, and of course, the only ones who show up are the two older ones. He asks where the bird went, and Don Pedro goes ahead and answers that Don Juan was the one keeping watch at the time, and even says that his youngest brother is the one who set the Adarna bird free (at least, judging from the fact that it was Don Juan on duty).
From what I understand of this, Don Fernando doesn't really buy it, and tasks the two to find Don Juan so he can find out the truth. And so, Don Pedro and Don Diego go off into the mountains to look for their brother.
It's amazing that Don Juan, yet again, despite being the one directly wronged by his two brothers, boldly advocates for them in front of his father.
Considering the heavy Christian/Catholic influence in this work, I would say that Don Juan here is either something of a Christ-like figure, in the sense that it's like how Jesus intercedes for sinners despite being rejected by most and even nailed to the cross, or possibly an example of an ideal Christian, or a reminder of the former. Of course, running away to hide the truth to divert from punishment isn't really ideal...
When it comes to the bird cage incident... This really shows that even if someone has been forgiven or vouched for, if they don't realize what they've done wrong, don't truly repent or they don't really think that they did anything wrong when they actually did, it still leads to doing more sin.
I'm just glad that the king at this point is interested in knowing the truth, and didn't really just accept Don Pedro's statement as the whole thing. But then again, considering that Don Pedro has already done something bad to Don Juan before, it wasn't that far off to think that maybe he did something of the sort again.
Right now... I guess we'll just have to see what happens next.