Darker than it seems

What would be the appropriate response to your future mother-in-law requesting you to seduce her husband? Well, nothing! I am pretty sure no self-respecting person had ever asked that.  
“What the freaking hell?” I reacted, unafraid to offend her. “Sorry. I am not a whore. You should hire someone else for this task. I may not be in the best life position, but I have standards. Already, I have stooped low enough by seducing your son. I can’t do the same with his father.” 
Mrs. Sinclair gave me a blank look. Either she was about to yell at me like Nathan or throw another tempting check on my face. “I understand your anger. I am not asking you to sleep with him. Spending alone time with him in sexy outfits shall be more than enough. You know how we women flirt subtly? Be so subtle that he can’t blame you for making a move on him later. Mislead him with your youth and beauty.” 
Unbelievable! They were all the same. Mrs. Sinclair may be polite with her words. However, like most wealthy people, she also believed all needy people were puppets she could control with her riches. Instead of making her employees deal with her mistakes, she should focus on getting her life together. As I couldn’t say that directly to her face, I took a calmer approach. 
“This has gone too far, Mrs. Sinclair. Pardon me, but you can’t trap your husband using your son’s fiancé. If Mr. Sinclair is unfaithful, Nathan will catch him eventually. In the meantime, you must do something about your situation with Doctor Williams. You can’t have both worlds. You have to accept loss and defeat from somewhere,” I said. It was important to give her a reality check while maintaining respect.  
A storm of tears poured from Mary’s eyes. She covered her mouth to muffle the noise and lowered herself to her knees.  
I avoided looking at her as I feared sympathy might force me to make some horrible choices like her. The mere thought of flirting with Nathan’s father made my stomach turn. There was nothing I could say to comfort her now without giving in to her satanic demands.  
“You’re right.” Mary began, fisting her hair. “I am a mess. I am more of a mess than my husband. Until Nathan finds him more at fault than me, I must remain quiet.” After crying for a good while, she got back on her feet. “I need to have a word with Williams. You shall know my decision very soon.” 
Instead of making me leave, Mrs. Sinclair walked out of her bedroom. The sound of her heels slowly becoming distant was a relief. I wasn’t sure why I cared so much about her when she was willing to use me in any way possible to benefit her.  
Initially, I was against the idea of getting on Mr. Sinclair’s side, but knowing how childish his wife was, it wasn’t fair to not give him a chance. I soon exited Mary’s room to meet Frank. It didn’t take me long before he came right to me. He must have been keeping an eye on me, waiting for the perfect time to converse. 
“Spying on me?” I started.  
Frank smiled at me smugly. “Was there any need to do that? I thought you were already coming to see me. You now wish to meet Mr. Sinclair. It must have been a blast attempting to reason with Mrs. Sinclair.” 
I grunted, throwing my hands frustratedly in the air. “Why is she acting like a new teenager? She is not sure about anything. How am I supposed to help her? And you would not believe what she said to me...” 
“She asked you to seduce her husband, didn’t she?” Frank spoke, blowing on his nails.  
“How the hell did you know that? Has she done this before? Does she have a reputation for this?” I asked, astonished by his guess. 
“I hope not.” Frank rolled his eyes. “It helps her situation to make her husband look bad. You are an averagely pretty young girl who has a soft corner for her. It made sense for her to demand that from you.” 
Something was off about the situation. I had a feeling Frank knew more than he was admitting to. Upon learning about Mrs. Sinclair’s affair, he didn't act much surprised. Looking back, I could see his shock was more around her pregnancy and the desire to keep the baby.  
“What do you know, Frank? I know there is more to it. Did Mary have more affairs in the past? Tell me everything,” I demanded. 
Frank laughed sarcastically. “So now you want my help? What about loyalty? I thought you were so sure about whose side we needed to be here. Shouldn’t you be Mary Sinclair’s loyal follower? I thought you had picked a team.” 
“Forgive me,” I said. “Not many people have been kind to me. I only wanted to pay her back for her generosity by guarding her secret. I should have listened to you.” 
Frank walked up to me eerily mysteriously. It seemed as if he were about to slap the biggest secret on my face. “Listen to me carefully, girl.” He shook his finger at me. “Everyone in this house is more guilty than they look. The employees like to gossip a lot. About half a dozen new rumors are flying around the estate. I don’t know what's true, but what I know are dark secrets about their past. Mary Sinclair has had many affairs in the past. What shocked me was that she chose her son’s doctor this time, which is very unusual of her. If you don’t want the people residing in this mansion to sell your soul without your knowledge, you better listen to everything I say.” 
“Do you understand?” he repeated. 
“Yes,” I replied in a trembling voice. I didn’t know what he meant by dark secrets, but my fearful mind had already imagined murder, Satan worship, and human sacrifice.