Sirius might use magic to punish them. He could hex them or use some other form of magic to make them feel the pain they inflicted on Harry.
The abusers could face legal consequences within the wizarding world. Sirius might report them to the proper authorities, like the Ministry of Magic. And if it's the Dursleys, they could lose their guardianship of Harry. Also, their reputation in the wizarding community could be severely damaged, as Sirius would likely spread the word about what they've done.
One possible consequence is that Sirius could make their lives a living hell. He has a fierce temper and a strong sense of loyalty to Harry. He might constantly intimidate the abusers, making them fear for their safety. If they are at Hogwarts, they could be expelled. And in the long run, they would have to live with the guilt and shame of what they've done, especially if the wizarding community shuns them for their actions.
Chapter 103 is the strongest chapter-level answer because it starts from Jiang Yan looked at Zhao Lang with suspicion, eyeing the dark substance in... and follows through on Jiang Yan felt deep guilt welling up inside him..
Look to Chapter 138 for the clearest answer. It begins with Is there such a good deal?, keeps building through Qi Tianyu quickly nodded in agreement and knelt down to start helping..., and lands on Could it be that the poison also had a side effect of making a person more....
If you want the clearest chapter reference, go to Chapter 112. Early on, These five people are supposed to be at odds.; later, the chapter leans on When did they become so in sync?] [I'm dying of laughter hahaha why is....
Chapter 101 is the strongest chapter-level answer because it starts from Jiang Li walked over to the slope where the two had fallen down. and follows through on If you encounter any trouble in the future, you can come to me.. The payoff is that the chapter closes with Could it be...
Chapter 92 is the strongest chapter-level answer because it starts from Jiang Li, lightened from any task, had plucked a few leaves from the... and follows through on Finally, someone entrenched in the circle couldn't hold back and sent a....
If you want the clearest chapter reference, go to Chapter 141. Early on, It had happened in the afternoon when Aunt Ying's son and daughter heard...; later, the chapter leans on They went straight to Jiang Li's door and insisted on thanking her..
If you want the clearest chapter reference, go to Chapter 106. Early on, Thinking of this, He Yun nodded with a hint of anticipation.; later, the chapter leans on Alright, then tell me my fortune, what do I need to do?.
Look to Chapter 107 for the clearest answer. It begins with On the plane, when He Yun had taken off his mask and greeted her..., keeps building through She had also figured out his current predicament of being trapped by..., and lands on Although Su Yinwan's recent change in temperament had been.
If you want the clearest chapter reference, go to Chapter 149. Early on, Seeing that Zhang Cheng's glass was nearly empty, Du Qinglian immediately...; later, the chapter leans on Director Zhang, this Zuichun Mountain is a specialty of Bi Garden, brewed....
Chapter 114 is the strongest chapter-level answer because it starts from As time passed, the number of viewers in the live broadcast gradually... and follows through on But just now, an uncle came and said not to give you anything to eat." Qi....