(Covers information from Anderson's universe)
"To answer your question. With the exception with a few technological upgrades, yes. I am the original Dr. Alexander Roland Isaacs."
— Isaacs introduces himself to Alice
Following Dr. Charles Ashford's development of the T-Virus, Isaacs found its mass-production to be a profitable necessity. James Marcus, Umbrella's co-founder, disagreed after being informed of the potential lethal side-effects. Albert Wesker suffocated Marcus under Isaac's orders. Isaacs then took Marcus's daughter, Alicia, under his wing to run Umbrella Corporation as partners.
Isaacs had modifications to his body done, which granted superhuman physical and mental traits. He now had a computer that predicted any actions that an enemy could do and a life support system to help him survive ordeals that could otherwise end with death.
An "Orchestrated" Apocalypse
During a conference with the Umbrella High Command, Isaacs discusses how problems in the modern world are going to lead to the end of it. Thus, he proposed a solution by which Umbrella creates their own apocalypse, under their own terms via the T-virus. Alicia, having learned of Isaac's plan, ensured a video recording of the meeting and transferred the file to the Red Queen program. After the beginning of the Global T-Virus pandemic, Isaacs entered stasis in the Hive with the rest of Umbrella High Command and thousands of employees. Two different clones would continue his work while Isaacs was in stasis.
Awakening and death
After Alice, a clone of Alicia Marcus who had been fighting the Umbrella Corporation began making her way to the Hive to get the anti-virus capable of ending the Global T-Virus pandemic, Albert Wesker had the Red Queen wake Isaacs and Alicia.
Upon Alice's arrival in the lowest level of the Hive, she was confronted by Isaacs who demanded that she drop her weapon. Isaacs threatened to smash the only vial of the anti-virus in existence which would render it useless due to the Hive being a closed environment. With Doc holding Alice at gunpoint and Wesker holding Claire Redfield, Isaacs reveals himself as the real Isaacs who has been technologically upgraded. As a result, Isaacs predicts Alice's moves and warns her not to try. He then reveals Alice's true history as a clone of Alicia who Isaacs is eager to have die so that he can gain full control of Umbrella. Isaacs is aware of Alicia uploading the recording of the meeting concerning his plan to the Red Queen and recognizes that the Red Queen has betrayed Umbrella. Alicia realizes that while Isaacs owns 50% of the company, Wesker is just an employee and fires him. This allows the Red Queen to act, dropping a door on Wesker's right leg and crushing it. As Alice and Claire attack, Isaacs flees with the anti-virus, only needing to keep it away from them long enough for the last human settlement to be destroyed to win.
Isaacs enters an elevator where he forces the Red Queen to deactivate herself. As the Red Queen does so, she taunts "Doctor Isaacs you and the Umbrella High Command. You are all going to die down here." Alice and Claire enter the elevator where Isaacs' technological enhancements enable him to predict their moves and dodge their bullets. Isaacs' fight with Alice takes them to the laser grid which he activates. When Alice dodges the lasers, Isaacs engages her hand-to-hand in the room, proving more than a match for Alice. Isaacs throws Alice around and even cuts off the fingers of her left hand with the lasers before discovering that she has dropped an activated grenade in his pocket. The grenade seriously wounds Isaacs who apparently dies moments later. Alice then takes the anti-virus and heads for the surface.
Shortly after Alice departs, Isaacs is revived by a life support system within his body and makes his way to the surface just before the Hive is destroyed by explosives planted by Alice. As Alice drops the anti-virus, Isaacs appears and catches it, holding Alice at gunpoint. Before Isaacs can kill Alice, his clone appears with an Undead army and is shocked to see himself there. Isaacs informs his clone that he's the real Alexander Isaacs while the clone is just a copy. Enraged and refusing to believe Isaacs, the clone attacks him, stabbing Isaacs repeatedly with a knife. His clone's attack causes Isaacs' life support system to fail, killing him. Isaacs' clone is killed moments later by the Undead, allowing Alice to retrieve and release the anti-virus.
The next morning, Alice is informed by the Red Queen that Isaacs' death allowed her to reactivate herself and recall the Umbrella forces. This combined with the release of the anti-virus foils Isaacs' plan to end humanity.
Isaacs is shown to be a ruthless man who is willing to go to any lengths to get what he wants. To this end, he murdered his business partner when the man disagreed with him and raised his daughter as his own solely to have control of Marcus' half of Umbrella through her. Isaacs has no problem with murder and genocide and shows a disregard for human life that is psychopathic. Isaacs also displays sadistic characteristics such as his glee in informing Alice of her true nature as a clone and in his treatment of Alicia after being awakened from stasis. Also, despite raising Alicia as his own daughter, Isaacs lacked any sort of care or affection for her. Instead he stated he couldn't wait for her to die and called her a colossal pain in the ass, showing he'd only kept her around to control her half of the company. Because Alicia caused the actions of her copies, the Red Queen and Alice, to be troublesome to him, Isaacs dubbed them the "Trinity of Bitches".
Isaacs is also deeply religious, believing in God and that they need to create an "orchastrated apocalypse" similar to the Great Flood to cleanse the world of most of humanity. During his meeting with the Umbrella High Command, Isaacs goes so far as to use a Bible and religious rhetoric to demonstrate his point. As shown with his clone, this is not manipulation on Isaacs part and he truly is deeply religious and believes in everything he says to the Umbrella High Command. However, his fanatical belief does not extent to the level of religious zealotry that his clone developed and as such Isaacs still retains some of his sanity.
Isaacs is shown to have a low opinion of clones, appearing to see them as mere tools and nothing less, simply cheap copies of the original. When confronted with his own clone, Isaacs was utterly dismissive of the man, not seeming to find him worthy of his time beyond briefly stating that he was the original and the clone was not. Isaacs found the idea that the clones are programed to believe they are the original highly amusing as shown when he taunted Alice over her true nature. This was ironically his downfall as his insane clone's belief in this fact was so strong he attacked and killed his original self over it.
Powers and Abilities
Due to technological upgrades, Isaacs exhibits superhuman abilities. By looking at objects and a person in relation to them, Isaacs's mind can calculate probabilities of possible scenarios in regards to the object and person. Amongst other things, this gives him the ability to dodge bullets by calculating their exact path and quickly evading them. Isaacs' upgrades also grant him superhuman strength, reflexes and durability that allowed him to overpower Alice despite her own superhuman abilities.
Isaacs is shown to possess a life support system as part of his upgrades that can revive him from near death and keep Isaacs going despite serious injury from a point-blank range grenade blast. However, this life support system has limits and multiple lethal injuries, such as the many knife wounds delivered by his clone, will cause the life support system to fail and Isaacs to die.
- Isaacs is the true main antagonist of the Resident Evil film series, having orchestrated the events of the movies though he only plays a direct role in the final movie.
- Following the death of his clone in Extinction, multiple characters are shown to have believed Isaacs to be dead, having believed his clone to be the real Isaacs.
- While Alice has faced the three versions of Isaacs shown in battle, she never actually killed any of them personally. His first clone was killed by an Alice clone, the real Isaacs was killed by his second clone and his second clone was killed by an Undead.
- Despite his second clone being created with all of this Isaacs memories, knowledge and personality, this Isaacs isn't as extreme in his behaviors as his clone. Due to his experiences after creation, the Isaacs clone appears to have transformed into a more sadistic and insane version of the original Isaacs. The original Isaacs also lacks the level of zealotry his clone possessed.