Caspian
Caspian will immediately clear his schedule so he can stay with you. He'll spend the whole day with you in your bedroom, reassuring you that there's nothing wrong with you and whoever bullied you has no idea what they're talking about. He'll wait until you've fallen asleep before calling Peter and Edmund to help him take care of the bully.
Peter
Peter will straight up challenge your bully to a duel. If you need comforting, he'll call Susan or Lucy to take care of you while he beats them. After they lose, he tries to have them banished from the kingdom.
Edmund
Edmund would bully them right back. He'd make a snide remark every time he saw them. He'd probably assign them as many crappy jobs as he could. Cleaning the stables, sharpening the swords, dishwashing etc. If they refused he's put them in the stocks.
Eustace
Eustace would find out their most embarrassing secret and blackmail them into leaving you alone. He'd tell you he took care of them but not how.
