Well I think for someone like Voldemort, Azkaban couldn't hold him. And I think he is nastier than the Demeators, he would have given them nightmares if they tried to suck anything from him. He never knew happiness in her life. Yes he had moments where things worked out for him, but not happiness like Harry had you know.

For Bellatrix I think it just increased her craziness. She thrived on the pain of others so I think getting to relive those moments over and over again for years just pushed her over the true edge of sanity. The Malfoys wouldn't last out a year in Azkaban I don't think they are truly as evil as the rest of their fellow death eaters, certainly not Cissy. I think Lucius talks a good talk but when you get right down to it what has he ever done for the cause? in OOTP he didn't do anything but demand the prophecy and all that jazz. So I think he joined the dark side because of his family and it looked like it was something fun to do. Sort of like why Regulus joined. If push came to a shove I don't think Lucius would hurt anyone like Bellatrix of Voldemort would do.