She was also Mr Saxon's representative on the project. She believed she was not just a co-worker and she loved Lazarus though he didn't reciprocate.
Sylvia was aware of Lazarus' cruelty and observed that the process and his new found youth had only made it worse. When Lazarus mutated after his rejuvenation went faulty he drained the life out of Sylvia as he needed the energy for the mutation to stabilise. (TV: The Lazarus Experiment)