The "Hands of Blue" were a pair of mysterious men, who wore suits and blue gloves. They were contractors to the Union of Allied Planets and were in pursuit of River and Simon Tam. Anyone who had any form of contact with River, even Alliance personnel, was killed without mercy with the use of a sonic device that induces massive bleeding from every orifice.
Behind the scenesEdit
The pair are never officially named in either Firefly or Serenity. In "The Train Job" DVD commentary, Joss Whedon refers to them as "the men with blue hands" and "the blue-hands men". IMDb's cast listings name each of them as a "Blue Glove", perhaps the most accurate moniker. However, "Hands of Blue" seems to have become a fanon name for the otherwise unnamed pair, from River's "two by two; hands of blue;" litany (possibly in reference to there being four blue-gloved hands between the two men, or to the fact that the men are merely one pair and may be followed by more like them, and the double-meaning for blue, as in, hands of Blue Sun.)
In the Serenity comics, the blue "gloves" are shown to extend to and cover the upper body as well. They were finally killed when Serenity's engine flare incinerated them, and the Alliance passes the assignment to retrieve the Tams to the Operative, explaining why it is he and not them in the movie Serenity who is chasing them.
It is possible that they are cyborgs, as Hands of Blue 1's upper body looks metallic and appears to have screws in it; also, this would explain their immunity to their own device. Blue 1, in the television episodes, has a stiff, mechanical quality to his movements, and his whole face is held rigidly in place most of the time.
The rhyme by River was even referenced in the TV show Castle, in hand actions made by Nathan Fillion's character, the eponymous Richard Castle, at a crime scene when he himself dons blue gloves to avoid contamination.