Sayid is a former interrogator for the Iraqi National Guard. He saved his love, Nadia, by releasing her from prison. He joined with the Unites States and Australian governments to breakup a terrorist cell. After this, he is given the whereabouts of Nadia and books passage to LA.
Of course, he ends up on Oceanic 815 and never makes it to Nadia. Sayid is constantly trying to put his past behind him, but is forced to use his “skills” over and over again. The survivors of the plane crash enlist his “help” in interrogating Ben, the leader of the others, when he is captured.
Sayid is one of the Oceanic 6 that escape the island. He finds Nadia and they are married. Nadia is killed by a speeding car and Ben uses this to make Sayid do his bidding; the killing of men affiliated with Charles Widmore.
Sayid refuses to return to the island, but fate has something else in store for him. He is picked up by a bounty hunter named Ilana and put on the Ajira flight that ends up crashing back on the island.
Sayid is shot while helping Jack detonate the bomb that kills Juliette. He is taken to the pool at the temple in an attempt to save his life. He seems to die, but not so fast. Several hours later, he sits up and is very much alive.
The Man in Black makes an offer to Sayid that he can not refuse. If he helps the Man in Black, he will make sure that Nadia is brought back to life. Sayid turns in to a shell of his former self and does all that is asked of him. At least until it comes to killing Desmond. He can not bring himself to do it. He joins with Jack in an attempt to leave the island and the Man in Black. When they find that they have been tricked in to carrying a bomb aboard the sub they’ve high jacked; Sayid grabs the bomb and sacrifices himself in hopes that the rest will survive. He shows us again, that he has a heart of gold.
In the flashsideways, we see that Sayid’s brother is married to Nadia and that they have two children. Sayid is still very much in love with her, but never acts upon it. He is forced once more to use his “skills” to save his brother. He ends up in jail and is found by Desmond. He is reunited with Shannon whom he fell in love with while on the island. They touch and remember. They join their friends with happiness finally filling Sayid’s heart.