Elika is a new character in the Prince of Persia universe - a Princess of the Ahura, she is introduced in 2008 release of Prince of Persia. She possesses magical powers that stem from the Fertile Lands and the Temple of Ormazd, the God of Light. She assists the Prince in his attempts to escape the confines of the desert and plays a very helpful role in the overall gameplay by assisting you with combat (as a part of various attack combos), puzzles, traps, and essentially "bailing you out" of many situations using these magical powers.
Elika is first introduced in the opening cutscene of the game while the Prince is out in a desert storm looking for Farah, his donkey. Elika is seen running from guards carrying halberds and jumping right on top of the Prince. At this time we have no idea who she is, only that she is being chased and the Prince starts to follow her. Soon the Prince sees a regal man in the distance yelling out asking why "Elika" is running from him. From there the Prince follows Elika until he nearly falls to his death and his saved for the first time by Elika's magic. This is the first she uses her "bail out" magic, but henceforth you'll see it whenever the Prince is about to fall to his death, be killed by a Corrupted, or sucked in by Corruption - essentially a plot device similar to the Dagger of Time in Prince of Persia: The Sands of Time.
Elika possesses amazing powers and they become part of your arsenal during the game. Her powers can be used in combat as part of combo's - "Elika's Combos", and she must also cleanse the corrupted Fertile Lands using this power.
Elika is a very serious minded Princess who stays focussed throughout her ordeals. She is the one prodding the Prince and urging him onwards when he seems to be distracted or stray from their mission of healing the Fertile Grounds and ultimately imprisoning Ahriman. You often see her admonishing the Prince for his irreverent attitude and carefree view of life.
Elika and the Prince share ironic banter throughout the game. She is more serious than the Prince but shares in some of his humour, especially countering his quips with laconic repartes that make him look foolish. This back and forth is a strong part of the chemistry and relationship between Elika and the Prince. Her seriousness serves as a good contrast to his constant jokester's view of the world.
Elika's father is the King of the Ahriman. His mother was Queen, but had died 3 years prior to the incidents in the game. Elika's mother loved the Gardens in the palace and often took children there to tend the plants. When she died, the kingdom of the Ahriman slowly faded into disrepair.