Not much information is given on her time in Azkaban but i'm sure many of you are wondering how she survived. Many people lost the will to live in one or two years so how did she survive fifteen? Well, like her cousin, Sirius Black survived for a similar reason. As we know, Sirius survived because he knew he was innocent and the dementors couldn't take that away from him because it wasn't a happy feeling. He also survived on his obsession for revenge. So basically, Bellatrix survived because of her obsession with Voldemort, she strongly believed he would return and it wasn't exactly a happy feeling so the dementors couldn't take it away.