Radium

Radium is a Metal from Homeworld. She is part of the Radioactive Metals and is to blame for the infection of radioactivity into the Metals (that ended up killing 1/5th of their population). Her co conspirator was Polonium, who was considered her significant other. She is incredibly intelligent and therefor incredibly dangerous. She integrated herself into the Metals society, helping with the sciences and other advances. However, it was discovered that she was purposefully infecting other Metals with radioactivity, essentially either killing them or corrupting them.

She died during the Takeover.

Biology
Radium stands at about 3/4 of a Diamond's height. She has familiar human proportions, a very unusual trait for Radioactive Metals. She wears a simple sleeveless dress. Her white hair is tied up in a braided bun at the back, with her long bangs tied up in the front. She has glowing green eyes and her entire body emits a greenish glow as well.

Biography
Radium came on a bit later in the Metals' history, arriving with Polonium. She appeared to be incredibly proper and intelligent, as well polite as she began to aid others in the scientific advances of the Metals' society. The Metals were very much willing to accept this aid, and she quickly became a high member of society. However, it was speculated that she might've been infecting other Metals with radioactivity, something the Metals didn't understand entirely up until this point. Radioactive Metals had only recently appeared and most were unintelligent beasts according to the Metals. These accusations and such were pushed aside however because of how much help and advancements she had given so far.

This came to a screeching halt at the confirmation that she was infecting others. It was also discovered that radioactivity was essentially corrupting Metals if they weren't killed by it. The remaining Metals of this plague were Promethium and Technetium, Technetium becoming infected because of close proximity with her in the work place and Promethium being one of the victims she had purposefully infected. Radium and Polonium, and all other Radioactive Metals (except for Technetium and Promethium) were subsequently locked into the Pit, a prison designed specifically for these Metals. It was also discovered at this point that Lead was capable of controlling these Metals as they were immune to the radioactivity and they seemed to be able to create a barrier, their poisonous touch also being incredibly dangerous to these Metals.

Radium spent most of the remainder of her days locked up, although it was revealed that she did not have it as bad as the other Metals had it in the Pit as she had conspired with Lead. When the Takeover happened, this was revealed as Lead and Radium escaped the Pit together and were able to keep Gems and other dangers away together. However, once Lead deemed it was safe and they had survived, Lead killed Radium claiming no one would want a radioactive Metal surviving anyway.

Behind the Metal
Radium is an element and an alkaline earth metal on the periodic table. It was one of the first radioactive discoveries made by the Curies (Marie and Pierre). Along with polonium, radium aided the two scientists in researching radioactivity and their effects, benefits, and properties. Radium was more of the favourite of Marie Curie's, as she discovered it, and ultimately killed the Curies with radiation poisoning (although other radioactive metals, such as Pierre carrying around uranium in his pocket, were the other source of this).

Because of this, Radium is intelligent and advanced the sciences in the Metals discovery, but ultimately lead to the demise of 1/5th of the Metals. She is also female in representation of Marie Curie, as well as "radium girls", a group of female workers that became infected with radiation poisoning while working with radium for glow in the dark watches.