But two characters pop out alone: Penny and Eloise.
They are related by marriage. Penny is the daughter of Widmore. We can infer from his back story that when he left the island to the main land, he had a child (Penny) which led to his banishment. He later married Eloise and together they had a child, Daniel, the scientific genius for whom Eloise desperately protected in the sideways world.
Penny grew up as part of the privilege class in England. She has aspects of being spoiled, but also has a rebellious streak against her father (as would later turn into her affection for Desmond). Desmond was the anti-Widmore, a man with little ambition, unmarketable skills and lack of commitment. Dez was a drifter, a loner, and man without a cause. Penny never needed Desmond, but when Desmond tried to win her back and lost at seas, he found out that he needed her.
Eloise was part of the plot to get Desmond away from Penny. Eloise was the watch clerk who told Desmond about life's "course correction," people die no matter what events intervene to delay it. Desmond was told he had a great role to play, but he did not believe it. That role was to set sail in a solo race to crash into the island - - - to be trapped there pushing a button that would keep the island in a snow globe.
The reason why Eloise wanted Desmond removed from Penny's life was that she was protecting Daniel from awakening. She knew that Penny had feelings for Desmond, and if Penny re-awakened those feelings in the sideways world, Eloise fantasy after life would be destroyed. So she kept Penny's happiness at bay for the sake of her own selfish goal of being with her son forever.
Her son, if he remembered Eloise killing him in the time travel episode, could have gone off with the other island castaways to the church and into the light, never to be seen again. Sending Desmond to the island prison was a way to prevent that event from happening.
Without that, Eloise would have no bonds to keep her in the sideways dream. Her perfect marriage to Widmore was a ruse since he had not awakened to the island past - - - and their feud/break-up over the island's control. Penny would not be awakened if Desmond was kept at bay, traveling the world at the behest of Widmore (or more likely Eloise's prodding him). Penny would have continued on in a privileged status that she had pre-Desmond relationship, not knowing what she was missing in her life.
If the baseline for the show was love, then the stories of Penny and Eloise demonstrate two sides of the same coin. Penny, in a blissful ignorance and Eloise, in a conning manipulation in the sideways realm. But in the island sphere, it is proactive Penny trying to re-connect to lost Desmond, while Eloise tries to right her wrong caused Daniel. One is a mother's love to an extreme, and the other is a couple's triumph over tragedy.
