(Please Note: this is all a mix of pure speculation with some information drawn from the series. It contains canon information but it is mostly Author’s assumptions.)

Emma’s father was an abusive drunk, which has made Emma wary and standoffish from making meaningful relationships with men. She made her mission in life to be the top of field and be strong, she did. She excelled in her education and was one of three women to make it through the program at Caltech (‘Mrs Sherlock’).  She was noticed by Rittenhouse, they recruited her and she later worked at Mason Industries and became the female pilot for the time machine. She worked hard to climb the Rittenhouse ranks to be as close to the top as she can. She’s one of their best and most skilled operators.

After working hard to be the best, sacrificing her social life and 10 years of isolation in 1800s; Emma finds there is something alien about meaningful sexual relationships and forming genuine emotional connections to her. She however understands that her beauty and sexuality are exceptional tools she can and does use to her advantage. She dresses for herself, how she deports herself is more of a well-made mask to show that she is a strong confident woman.

When Nicholas meets Emma, she is the woman who saved his life with her medic skills in 1918 (‘The War to End All Wars’). As they spend more time together, he grows attached to her. She’s a strong, capable and beautiful woman who is deeply loyal to him. As time passed, he grew to trust and admire her. He showed her as much when he sent her on a mission 1919 to deliver a message instead of doing the ‘dirty’ work. It annoyed her to be sidelined, the mission to take away her right to vote and perpetuating the stigma of ‘putting a woman in her place’ upset her. But she doesn’t let it show, as she is a loyal Rittenhouse agent. But she does make the mission fail and killed her comrades to maintain her control and position (‘Mrs Sherlock’).

When she returned, it was effortless for her to lie to Nicholas. She flirted with him using his earlier words to her advantage to cover her deception as Nicholas wanted her to come back to him safe. Nicholas responded well to her feigned interest in him, she tried to use it to boost her profile in Rittenhouse to share ideas and possible tactics. Nicholas reached out to her, she almost flinched at his touch as it’s been a very long time since she has been touched in a non-violent or perfunctory manner. He told her ‘Later’ and he kissed her, she smiled as she realised she could use their relationship to her advantage but there is a part of her that is secretly thrilled by their intimate connection. Maybe one day, she could be genuinely attracted to him. The real drive is that she wants power; to ‘Queen’ at his side and reign over Rittenhouse with him. There is something oddly romantic and archaic about it.

However, for Nicholas, he is emotionally involved and blinded by his admiration of Emma. He is a man outside of his own time, while he has a strong vision for Rittenhouse’s future; he feels lost. His Great Granddaughter Lucy has betrayed her legacy and his granddaughter Carol protects her. He feels a point of contention on the matter while Emma he believes is truly loyal and faithful to him. The two carried on an affair until on night, Carol took him to a cemetery. She showed him his daughter’s grave. She reminded him what Rittenhouse was based on Legacy, Family and blood. That Emma’s faith in him was fleeting (‘The General’).

Nicholas took Carol’s words to heart and sacrificed his relationship with Emma, to maintain his control and power over Rittenhouse. He slowly pushed Emma into a less dominant role in Rittenhouse and shut her out of the decision-making processes of their mission.

Emma became restless with the shift in their relationship, she could see Nicholas was too much of a traditionalist to see her as an equal. As a woman who is not a Rittenhouse legacy, she knew she would never be able to reach her goals. In 1888, fed up with being held back. She killed Carol and then shot Nicholas in the head. She had no remorse, as she took control of Rittenhouse and she was finally at the top through her own hard work and initiative (‘Chinatown’).