you were ranting to Celestia about how much you hate Ishimaru and you wish he would just die... You weren't serious of course because you aren't that cruel... But Celestia had a different idea

"How about we do it together?"

she was seriously asking you if you could kill Ishimaru with her and try to get away with it in the trials...

"That way he can't annoy you anymore"

the worst part is... She's serious about killing him and probably will kill Ishimaru with you without hesitation