User blog comment:Piyush Banerjee/Shin DxD 2 discussion/@comment-33939194-20190105040411/@comment-2601:87:8300:20D0:3585:7CAD:D59:E63D-20190105124948

Sorry I wasn't being specific what I'm saying and this can be argued that at first I doubt she thought Grayfia would join the Azazel Cup. Rias has her owned goals before knowing her participation such as her dream in RG or maybe to show her worth to Issei that she can stand by his side. You could also say that she might be testing herself to see how far she can go. It could be all of that, but when she found the truth behind Bina and confronting her things change. She wanted to prove herself even more in front of her sister and wanted to show her she's not alone that she has a family. Using the word bonus might not have been the right choice,  but that's what I meant.