She sees Shiroe as an trust worthy person and a brilliant strategic. She also has romantic sided feelings for his unique character like Akatsuki etc. Even though she doesn't want to believe that she has feelings for him. She's aware of that. Because that she tries to keep the terms as good as possible.
Upon meeting Akatsuki, due to the Assassin's short and petite appearance, Henrietta went gaga over her cuteness and has ever since made many (often successful) attempts to dress Akatsuki up in dresses and other cute garments. While she means no harm, this is actually disrespectful to Akatsuki due to her past experiences because of her short and young appearance.