So, here's Tess, Niko's younger sister by about a month. Unlike her brother, who is cold, distant, and just a little bit rude, Tess is warm, personable, and always polite. She's very supportive of her brother, and along with their butler, does her best to make sure he remembers to do things like eat and sleep.

The observant viewer may take note of the collar around her neck. This is no mere decoration, and the story behind it is actually the primary reason for why her brother's personality is so abrasive today.

You see, when they were both much younger, one of Niko's earliest inventions, an automated lumberjack, malfunctioned while he was testing it. The machine ran amok, and Tess (who was watching nearby) had her head sliced off by it.

Although she was the most severely savaged by the rogue automaton that day, she was not among those who were counted among the dead. The instant that he had seen her attacked by his creation, Niko ran to her side, heedless of the swinging axes and buzzing saws.

No one is quite sure how he managed it, but Niko was able to keep her from dying that day. Working feverishly and without rest, he constructed a miniaturized life support system, taking the form of her collar. When it was finished, and Tess finally regained consciousness, she hardly recognized her brother. Though outwardly his appearance had changed little, he had become moody and obsessed with his work to a worrying degree. She therefore took it upon herself to look after her brother as he had looked after her when she was close to death.

An interesting thing to note about the current version of her collar is that it allows her head to be detached without either her, or her body dying. In addition, the collar can be fixed to various machines, allowing Tess to control them as easily as her own body. While detached, she can still control whatever it was that she was last attached to, which has proven useful on a number of occasions.