And Antonin's hatred for Augustus was also legendary. There had been a time, long ago, when the two men would've considered each other friends. Certainly when her protector arrived at Antonin's house that first time after she left the window open, her teacher had been happy to see him and invite him in for tea. Their friendship soured soon after it became evident that Augustus" purposes for being in his house were a bit more nefarious than he cared for. When Hermione didn't return from France with the others after her first mission without him, her future husband considered removing his competition from the equation entirely.