@The Angry Dango of Doom
 
Adagio is bad-tempered and more manipulative, and Aria is always irritated or uninterested. So it leaves Sonata as the more pleasant choice, regardless of what bad things she had done.
 
 
@Beau Skunky
 
Perhaps Sonata would keep one as a pet, because the octopony looks too cute to be delicious.
 
By the way, the Japanese text used by the red octopus says, “Hey, Miss Sonata! Are you a kid now, or a squid now?” If you want to know why did the octopus think that Sonata is a big blue squid, here is your answer.
 

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@The Angry Dango of Doom  
Because she was the ditzy one, I suppose?

IDK where this meme of Sonata being the nicest/friendliest of the group. She was right there with Aria and Adagio kicking Sunset when she was down after Trixie’s band was called to the stage

@HorsesandMuchMOAR  
Just as long as it’s not an Octopony, they’re too cute to eat.
 

@Beau Skunky
 
And so it can also be a pun on what Sonata loves to eat. Perhaps she would appreciate a tako on a taco: in other words, seafood mixed with Mexican bread.
 

Tako is Japanese for “octopus.”