A former nobleman assassinated as part of a greater plan of higher doing. He was resurrected as a vampire by Mortanius. Enraged by his death and quest for his revenge, he didn't think of the consequences. He killed his assassins and was called by a higher power to restore the pillars and Ariel told him to restore the pillars, to find who orchestrated his death. He originally did it to find a cure for vampirism, but there isn't one. His quest led him to the Circle of Nine, the guardians of the Pillars of Nosgoth. Nupraptor was the first guardian he met and destroyed.

As he continues on his journey he gains magic spells, and new weapons and attacks. As the Serafan and bandits fall by the score, Kain Runs in to the other Circles of Nine, Malek, his Soul was fused to a hellish set of armor for failing the Circle of Nine and allowing six of them to die at the hands of Vorador. So he is bent on getting his revenge for his suffering. Kain did not defeat Malek, so he required some assistant.

Then he met Moebius the time guardian, who told him to find Vorador. He did and Vorador told him not to meddle in the the affairs of humans, it would bring him nothing but trouble. As Kain thought about the advise, he went on with his journey as he heard nothing.

Then Moebius points to Kain and have the people of the city attack him, as Kain is the final vampire left. He massacred all the people in the town then after Moebius. He decapitates Moebius. Then he journeys back to the Pillars of Nosgoth. When Kain got to the Pillars, He saw Mortanius was confronted by Anarcrothe saying it was his fault that Kain was destroying the Circle of Nine, and

Mortanius said he had to because all of them had been corrupted by Napraptor. Mortanius and Anarcrothe fought, because Mortanius wouldn't join him saying they exists for the the Circle; the Circle doesn't exist for them. Since Mortanius was the guardian of the Death Pillar obviously he won that fight. Then Kain stepped out form the pillars saying that he Mortanius will have to die also. Final fight you see Kain Kill Mortanius, but then his body transforms into another demon which had posses Mortanius. He tell Kain how he was a pawn in his plan to kill the whole Circle of Nine.

He encounters Malek again along with two other members of the Circle of Nine; Bane and Dejoule. Kain calls on Vorador to deal with Malek, as he relentlessly kills then other two. He makes his way to the Avernus Cathedral where he founds the legendary blade the Soul Reaver.

He defeats Azimuth deep with in the Cathedral. Then Arrives at King Ottmar's Castle, where he is capable of gaining control of Ottmar's army; So he can stop the Nemesis from invading and taking over Nosgoth. He needs to find the Dollmarker to restore Ottmar's Daughter to her original self. So another side quest begins; he destroys and receives the army of Ottmar to fight against the Nemesis. Before he reaches the Nemesis' stronghold he was sent into the past with a time streaming device, and he saw Moebius talking to the people of the city about kill vampires as a curse on their land which started the great vampire purge, and Moebius wanted to speak to King William, later known as the Nemesis.

Moebius arms him with Soul Reaver and tells him a vampire is after his life. So Kain encounters William and destroys him, and breaks William's blade. This was the final draw for the people to start the vampire crusade and try to wipe them out once again. Kain returned back to his own time to see Vorador being executed in front of him. The people believe that all the vampires are dead.

Then Kain Defeats him and Ariel appears and Tell him he is the final member of the Circle of Nine. So if he dies the World will be restored and new set of guardians will be born, or he could live and it would cause of his existence damn the world. He found out he was tainted when he was reborn as a vampire and it was setup for him to become the Balance pillar guardian.(Playing Soul Reaver 2 will tell you why he became the Balance Guardian.) He decides to live and rule Nosgoth. Few years later, He is General of an army destine to rule Nosgoth. Suddenly going into battle he was cast down from power, by a mysterious warlord. Barely live he was found by a vampire resistance who nursed him for back to health for 200 years. He finds out his army was slain, his vampire brethren nearly extinct, Kain is one of the last of is kind once again. With an agenda of vengeance, Kain shall unleash a wicked wrath to uncover the plot that threatens the land he seeks to conquer.