Studying the history and story of the executioners, all of them are in Rathuum for a reason. Some of them are there out of choice, testing weapons, punishing grineer, taking pleasure in pain.etc. Others are there under orders, either for punishment or pleasure. Regardless of reason, Rathuum does not discriminate between personality, affliction, history, faction, or race. Rathuum is judgement and bloodshed alone. Kela De Thaym is master of Rathuum and mastermind of the event, she knows it is a rigged display of grineer power, but she never expected the Tenno to step into her arena.

Then there's this frost. He has his back to a grineer army, almost as if not fighting but leading them as a commander or general into a war. They're holding up a tenno and using him as a weapon. Yet frost has his back to them. His rather menacing looking armoured helmet, hiding who knows what past. His collar is flared around his neck in a rather regal fashion, his necktie indicating his professionalism. The design on his chest mimics that of goat horns, inditating evil, or dark intentions, perhaps simply indifference. Is he an executioner? Is he a participant? Perhaps he is Kela De Thaym's new champion, or conversely simply a gladiator fighting only for the glory of the arena itself. Why has he turned his back on a tenno in pain? Is he simply a rogue?

There are many questions unanswered, perhaps even my bold marked guesses at the enigma are all way off the mark, but one thing is certain, an enigma of another sort lies beneath that mask.