|Portrayed by||Megalyn Echikunwoke|
|First appearance||Mommy's Bosses|
|Ability||Regeneration, Telekinesis, Super Intelligence, Phytokinesis, several unidentified powers|
|Parents||Richard Tyler, Lily Tyler (Deceased)|
|Siblings||Heidi Moore, half sister|
|Significant other||Shawn Farrell (formerly),|
Season 1[edit | edit source]
Lily discovers very shortly after her return she is pregnant. The baby inside her is aware at a level, making Lily able to feel unwell if there is danger or, in the case when Lily sees her daughter, Heidi, when the baby is jealous. Lily knows early on that the baby will be a girl.
When Jordan Collier attempts to stop Lily and Richard from leaving his complex, he touches Lily's stomach. The fetus inflicts severe pain on him, that even Shawn Farrell cannot fully heal months later.
As Lily is being driven to the hospital in labor, the trees lining the road actually bend down towards the car as it passes.
Season 2[edit | edit source]
After Isabelle's birth, Lily, Richard and Isabelle went on the run from NTAC and Jordan Collier , with Isabelle using several powers to aid the family in their situation. As they were being chased by a deranged family of "4400" haters, she first made fruit grow on plants and later forced the armed men to shoot themselves. The family were eventually persuaded to return to the 4400 Center, in large part because Isabelle seemed to trust Jordan Collier's sincerity. She also apparently healed the remaining damage she had inflicted on him.
However, Isabelle still sensed that Collier was dangerous and greedy. When his death was predicted in a vision of Maia Skouris', Collier asked Isabelle for advice. The baby Isabelle showed Collier a vision of what she knew he wanted to see - prestige and glory. This vision persuaded Collier that he was safe but he was assassinated shortly after.
As the 4400 became ill as a result of the promicin inhibitor, Dr Kevin Burkhoff stated he could develop a cure using uncontaminated blood that contained promicin. Isabelle had not been treated with the inhibitor, as her parents had gone on the run from NTAC before her birth, so her blood was used to heal Shawn Farrell and consequently all 4400s, unbinding their abilities. At the end of Mommy's Bosses she aged to adulthood, and walks naked into Shawn's office.
Season 3[edit | edit source]
Dr. Burkhoff finds a link between Isabelle's aging and Lily's sudden aging to that of an elderly woman. As Isabelle's body grows stronger, Lily's becomes more frail, inflicting diabetes, arthritis, and other diseases on her. Burkhoff believes the only way to save Lily would be for Isabelle to actually die; Isabelle tries to commit suicide by jumping from the roof of the 4400 Center, but is unharmed. She is chastised by Matthew Ross, who informs her that she is indestructible and of vital importance to the future. Lily finally dies of old age, after giving Isabelle her own grandmother's ring.
According to Ross, her purpose is to eliminate all of the 4400, as not everyone in the future believed they are a beneficial thing. This was confirmed later in season 4, when Isabelle was described by 4400 Curtis Peck as being the "ultimate weapon" of the anti-4400 faction in the future. Isabelle refused to believe it, saying that (as described by Shawn Farrell) being good or evil was a matter of choice.
Isabelle is still, however, a dangerous mixture of youthful innocence and deadly power. On Ross' advice, she begins a sexual relationship with Shawn, one that her father strongly objects to. She finally rejects Ross' influence, and plans to marry Shawn, despite his clear statement that he wants to end the relationship. Isabelle responds with a veiled threat, stating that they were the two most powerful people on the planet and that, without his "good" influence, she may do terrible things.
Isabelle begins secretly working with Dennis Ryland, to ensure "the balance of power" between 4400s and non-4400s is maintained. Promicin is extracted from her blood, and used in Ryland's super-soldier program. Still engaged to Shawn, her intense concern for his well-being leads her to torture and kill several members of the Nova Group in an attempt to track down Daniel Armand, who afflicted Shawn with paranoid schizophrenia. She is detained by NTAC but there is no evidence to tie Isabelle to the murders, forcing her to be released.
After the resurrected Jordan Collier bars her from the 4400 Center, leaving her marriage plans in ruins, Isabelle openly allies herself with Dennis Ryland. When Isabelle and Ryland find what is apparently the storehouse of stolen promicin, Boyd Gelder detonates a suicide bomb. This attempt to kill Isabelle enrages her, and she goes on the rampage, killing 4400s at the Center in an attempt to lure Collier to her. As she is about to murder Maia Skouris, her father manages to inject her with the serum sent from the future; instead of killing her (as everyone expected), it strips her of her abilities. She is then wounded by Tom Baldwin and taken into custody.
Season 4[edit | edit source]
In prison for her crimes, Isabelle is visited by Tom Baldwin, seeking information on his wife's whereabouts. Isabelle directs him to an art gallery, where a picture of Alana hangs, painted in 1885. How Isabelle knew this is unclear; it is implied that her connection to the future may have somehow been responsible, but is also likely that she saw the painting in one of the many books she read after growing to adulthood, and remembered it after the timeline was altered by Alana's re-abduction.
Isabelle is offered the chance to move to a less secure facility. She gives a blood sample, and is later told that the serum given to her by Richard also induced a fatal allergy to Promicin; she will never regain her abilities. However, the transport that takes Isabelle to the facility crashes in a car accident. Kyle Baldwin, at the scene because of his ability, helps Isabelle escape and takes her to his family's rural cabin.
In The Truth and Nothing but the Truth, Isabelle reveals that despite the fact she no longer has her powers, she has kept her massive intelligence and memory. Due to her knowledge of numerology and cryptography, Isabelle helps Kyle decode the White Light "bible", revealing essential information about the future of Collier's movement and a list of people who must take promicin.
Kyle and Isabelle later meet Collier, and form an alliance with him. Isabelle reveals the reason she wants to help Collier is to give her life meaning, and seek redemption for her past atrocities. Collier warns her that at the slightest sign of making him "nervous" her invitation will be terminated, presumably with her life.
After the movement journeys to Seattle, Kyle brings Shawn to meet Collier, and Isabelle tells Shawn that she knows he will never forgive her but she needed him to know how sorry she was for her past acts. When Maia Skouris enters Promise City to warn Collier his life is in danger, Isabelle tells Maia that she's sorry for hurting people Maia cares about. Maia scornfully responds that some things are so bad, saying "sorry" isn't enough.
When Isabelle's father Richard Tyler returned and met her at Promise City, he mentioned how sorry he was that he was unable to teach her right from wrong. He used his ability of telekinesis to stop the flow of blood to her brain to render her unconscious. He then gave her water that later caused her to regress until she was a toddler. Unknown to Isabelle the water had been influenced by a 4400 with the special ability to reverse aging.
In One of Us, after returning to the developmental stage of approximately two years old she resumes life as a contented and happy toddler with no memory of her adult life. Richard, her father, is happy. However, her mother Lily Tyler reappears in Isabelle's and Richard's lives. While she doesn't know how she got there she is unhappy about how Richard took away Isabelle's life as a young adult and all she had learned. Lily is really a projection into his mind by another 4400, Byron Lillibridge who vanished on February 28, 1966 and Kyle Baldwin in Promise City, although she appears and feels real both to herself and to Richard. She soon is returned to whence she came. Richard, realizing it was wrong to take away Isabelle's adult life reverses the youth process with the help of another 4400, Cora Tomkins who disappeared on November 2, 1950 (making her a contemporary of Richard who disappeared seven months later in May 1951). She was the one who produced the water like substance that reverses the aging process. She also has the ability to restore the person to the age that person was before and returns her to her early 20's age.
She and her father are soon captured by Tom Baldwin, who is really under the influence of an enigmatic anti-4400 faction from the future known as the "Marked" (which Matthew Ross was a member of). After regaining her powers and being strong-armed into helping the Marked, she resumes her bloody campaign against the 4400 and kidnaps Collier, but ultimately rebels once again, sacrificing herself to free Collier and freed Tom, who had come to Collier's aid beforehand.