This season of "The Challenge: Battle of the Exes 2" wasn't easy for the cast. Not only did they face off week after week in grueling contests, but they also had to deal with the loss of two veteran competitors. Diem Brown and Ryan Knight died within two weeks of one another in November. Both had competed on the most recent season of the hit MTV competition series, though Brown left early for medical reasons.

Tonight, more than four months after their passing, the cast reunites for a special show in which they will pay tribute to their lost friends. Previews for the special show Nia Moore, Zach Nichols and the rest of the "Challenge" gang being brought to tears as they share fond memories of Brown and Knight through the years.

Nichols reveals he spoke to Knight the day before his death, adding that the 29-year-old did not "function well" outside of the MTV house. Nichols says Knight's funeral took place in "the smallest town I've ever been to" but nevertheless drew a massive crowd. 

"He packed an entire auditorium with thousands of people, so that's something to be said about him," he says, adding, "You can't say enough good things about Diem."

Brown died Nov. 14 after a lengthy battle with cancer. She was 32. Brown made her initial diagnosis public on a previous season of the show. She beat cancer twice, in 2006 and in 2012. Multiple reports say Brown spent her final days surrounded by those she loved, including on-again, off-again boyfriend Chris "CT" Tamburello. According to Hollywood Life, the 34-year-old "Challenge" cast member popped the question on Nov. 9, five days before Brown died. 

Sources told Us Weekly Tamburello presented his beloved with a ruby ring. The entire proposal reportedly was filmed. Shortly after Brown's death, Tamburello revealed via Instagram that he now has the ring in his possession and keeps it as a reminder of their love. While he and the rest of the cast tried to wrap their minds around their loss, they were struck with more tragedy.

Two weeks later, on Thanksgiving morning, Ryan Knight was found unresponsive at a friend's home in Kenosha, Wisconsin, after a night of partying. Initially the cause of death was unknown. Autopsy reports, released March 18, now suggest he died from a combination of drugs and alcohol. According to TMZ, Knight had methadone, tramadol, cocaine, Xanax and traces of alcohol in his system when he died. During his time on MTV's "The Real World," Knight opened up about his struggles with drugs. He told his housemates he had been to rehab after getting hooked on painkillers in college.

"He was in and out. Drugs and alcohol had a grip on him," a friend told the Boston Herald. "He could be sober for a short time after rehab, but then he would fall into his same patterns."

The reunion special airs Tuesday at 11 p.m. EDT on MTV after the "S--- They Should Have Shown" special at 9 p.m. and the "The Challenge: Battle of the Exes 2" finale at 10 p.m.