Alec was the first darklighterr the Charmed Ones encountered. Alec fell in love with a mortal woman named Daisyy, who he was assigned to impregnate. He attempted to kill Leo, but Piper switched powers with him and managed to heal him.
He was killed by Prue who switched powers with him and killed him with his own touch of death.
As an evil being assigned to manipulate a good woman for an evil purpose to advance his kind and subsequently falling in love with her only for it to be his downfall, Alec's relationship with Daisy could serve as a precursor to the much longer story of Cole and Phoebe's whirlwind romance.
Powers and Abilities
Alec was a powerful darklighter who displayed the basic powers to teleport through black orbs and call for his crossbow. He had also shown the power to glamour his appearance, sense charges and is the only darklighter to display the touch of death which is the counterpart to a whitelighters healing ability. Victims of this power would die from their skin burning rapidly.
It's unclear if Alec also had the ability of pyrokinesis displayed when Alec was preparing to kill Daisy to prevent her from loving someone else and the rocks behind her erupted in streams of fire coming from it's centre. Alec was also highly resistant since Leo said that it would require the Power of Three to initially vanquish him suggesting that he may have been a Darklighter leader.
Prue and Phoebe confronted Alec just before he was about to kill Daisy and cast a spell to swap powers. Prue received all of Alecs powers including his touch of death and Alec received the power of premonition. Alec would have originally received Prue's power of telekinesis but Prue accidently received Phoebe's power when Piper also cast the same spell to revive Leo using his whitelighter power to heal. Before Alec could react to this change Alec was killed by Prue using his powers and received them back just before he died.