STEP FORWARD!
Will was twenty one at that time and they were in the fifth year of slavery when Gerald and Mason had this brilliant idea to let ten savages rape him. They reenacted what they had done to Ethan two years prior.
He still remembered how those savages touched him and got their pleasure from his body over and over again. He lost count how many times he lost consciousness only to wake up to them doing the deed without stopping.
If it was not for his good constitution, he would have died during the process, as they used his body as they pleased and didn't hold back at all.
However, at that time, he wished he had died. He wished the suffering would end that night.
Will still remembered how he heard Gerald and Mason laughed at him, among the labored breathing of the savages when they reached their climax by using his body. It was something that he would never forget. A 'nice' gift from Gerald for his lifetime.
The most frequent event that would haunt him when he had his nightmares.