Nicholas was a powerful warlock, who went after the Charmed Ones in 1999, after forcing their mother into a deal to give up their powers years earlier.
In March 1975, Nicholas tricked Patty Halliwell, the Charmed Ones' mother, into his apartment when she was pregnant with Phoebe. He had made her believe that Victor, the Charmed Ones' father called her to meet with him. He forced her to give up her daughters' powers to him in return for sparing her life. He also forced her to bless a ring that gave him immunity to the Charmed Ones' powers. After being tipped off by the grown-up Charmed Ones, Grams cast a spell to bind the Charmed Ones' powers shortly after Phoebe was born.
Discovering this, Nicholas used his Glamouring power to magically age himself and pose as a would-be suitor for Grams. Each year he would appear on the same day with a vase of flowers for her at exactly twelve noon. In the middle of the clock's gong, he would drop the flowers to see if one of the Charmed Ones would freeze it before the vase broke.
When he showed up in 1999, a year after Grams' death, Piper froze the vase just as he dropped it. When he unfroze, he realized that the Charmed Ones had their powers and tried to take them. He was eventually killed via the spell their Grams made up to help them kill him after they went back in time.
In 1999, he was resurrected by Abraxas, a demon of the Astral Plane. Abraxas stole the Book of Shadows and started reversing all the spells in it in an attempt to demonize the sister's powers. When Abraxas recited the Nicholas Must Die Spell backwards, Nicholas was brought back from the dead.
Nicholas then attacked Prue Halliwell in her office at Buckland Auction House but Prue was able to re-vanquish him with a spell. This time, a potion was not necessary ("Witch Trial").
Powers and Abilities
Spell Casting: The ability to cast spells and perform rituals.
Potion Making: The ability to brew magical potions.
Scrying: The ability to scry for lost objects or people through the use of a map and scrying crystal.
Blood Boiling: The ability to increase the temperature of blood to a boiling point, causing intense pain and eventual death.
Glamouring: The ability to assume another appearance. Nicholas used this ability to make himself appeared older.
Power Absorption: The ability to absorb the magical powers of other beings. As a warlock, Nicholas could absorb powers through an athame.
Immunity: The ability to be immune to magical powers, spells and potions. By having Patty Halliwell bless his ring, Nicholas became immune to the powers of the Charmed Ones.
Immortality: The ability to possess an infinite lifespan and an arrested aging process.