Viki is a recurring character in the Suikoden series with control over teleportation magic. When the player recruits her as a Star of Destiny, they may then use her ability to instantly warp to other regions of the world instantly. She is also able to make use of her teleport magic in battle. Her powers allow her to travel through both space and time, but she seems to lack control over the latter and will warp through time uncontrollably, which is generally how she travels from the events of one game to another. Over the course of the Suikoden series, she appears to follow a personal timeline removed from that of the series itself; hers is based on the order in which the games are released, rather than the order in which the games' events occur. It's not fully known where or when she's from or even what she is but she seems to be strongly tied to the gathering of the stars.
Though she controls powerful magic, Viki is a fluff-headed ditz and becomes confused rather easily. She is, however, very friendly to everyone she meets, and tries to remain cheerful no matter the circumstance.
In Suikoden III, there is another Star of Destiny called Little Viki. Unlike the childish elder Viki, Little Viki has the temperament and intellect of a mature adult, and often treats Viki as being beneath her for being so incompetent. How Viki and Little Viki are precisely related is unknown.