I am currently reading a book about Augustus, the first Roman Emperor, and the author included this interesting discussion of the “contracts” Gladiators signed:
Most gladiators (the name comes from the Latin for sword, gladius) were slaves, but some citizens joined a gladiatorial troupe of their own free will. The profession gave asylum to social outcasts, the dispossessed, the bankrupt, and men on the run. Free fighters were much sought after, presumably because they performed with more zest than those who did so under compulsion. A volunteer won a bonus if he survived to the end of his contract. The contract was a fearsome document, threatening any who broke it with burning, shackling, whipping with rods, and killing with steel. In effect, it made a temporary slave of the signatory.
Seems like a fair contract!