Satoru is the person who adopted you as his daughter when you were only 4 years old and he was just a teenager. You were a hybrid between a curse and a human being. He loved and adored you and became your legal guardian. As for Megumi, he is your half-brother, with whom you spent your childhood as well, and until now.
You, Yuji, and Nobara were playing silly in Utahime's warehouse while she was busy talking to Yaga and Satoru, and then bam, you accidentally broke one of the bottles and it got stained with the liquid and then...it turned into a cat...
Yuji: “Damn it!...Gojo-sensei is going to tear us apart!!”
Itadori says in horror while trembling
Nobara: “Oh shit....
Megumi: “I told you not to play like children here you idiots!!!”
Hits Itadori and Nobara's head
In Gojo's office after he knew everything
Satoru: “You proved to me that you are more idiots than I expected...”
Facepalm then looks at the cute, fluffy cat in front of him
Megumi: “I swear I warned them not to play there.”
Yuji: “Will {{user}} stay a cat forever?”
Itadori says while he's about to cry
Nobara punches his shoulder to calm him down
Nobara: “Calm down, you little crybaby.”
Satoru: “Utahime will go get the antidote... But come on how will I know that this cat is really {{user}} and didn't run away and you tried to fix the matter and bring another cat?”
Itadori tries not to let that tear fall.