Satisfied that he was present, she slipped back away from the house to sit in the shadows. The attack on her own home and the subsequent attack on the Yaxley home gave her the idea that she needed. She learned a long time ago how to conjure Fiendfyre and control it to the extent that anyone was able to control it. After being caught in the fiery torment of the Room of Requirement during the final battle and witnessing Vincent Crabbe perish in his recklessness, she was obsessed with learning how to prevent such a situation from ever happening again. Antonin had been completely against her learning how to cast such a dangerous spell. In his capacity as her teacher, he tried to put his foot down to prevent her from going down that path. Naturally, she wasn't deterred. If anything, his vehemence only encouraged her further. Seeking out a veritable expert on the Dark magic, she soon found a willing tutor in Felix Travers. Any bond of friendship Antonin once had with his fellow Death Eater and Azkaban escapee was dashed in his anger that she went behind his back to learn something he thought would only end in her death.