I've been with TDCJ over 32yrs. I was an STG(read gang) Sergeant for many years, and a PREA/Safe Prisons Manager for Region 3 for several years of my career. Prison rape, male on male sex, does occur. It's not condoned by the agency, and the agency does what it can to prevent it. Our classification system is set up, and has processes in place, to try and prevent it. But, it happens, not as often as people think, but it does happen. The voluntary stuff rarely if ever gets reported. Guys that are in for long periods of time, and know they're not getting out soon, may start looking at the known homosexuals and the weaker inmates as possible mates. Sometimes the couples work out, and sometimes not. They sometimes end up in fights. Sometimes the weaker inmates are extorted into performing sex acts. And, sometimes the gang members will pimp out a homosexual or a weaker inmate to other inmates in sex for money schemes.
Prison rape is usually about power and control. The predator gets a feeling of empowerment and control over the victim, and that's what they crave. It's not necessarily about the sex. I'll tell you that in all of the sexual assault investigations I conducted over the years very few resulted in prosecutions. Most of the time the inmates filing the complaints were using the system to get a housing change, or a job change, or they were trying to get another inmate into trouble. Most of the time there was no physical, or any other evidence, to substantiate their allegations. The agency prosecutes when they have the evidence to do so.
Something to think about, I personally would NOT want to be a young, white, small in stature, timid, person with a long sentence. Chances are high that person may be assaulted.