It's a zombie Arc, MC = scientist And working for the FL who is threatening him with his parents. MC And FL are working together in a lab And FL is taking his research as her own. She has no idea about science...
By zombie """arc""", does that mean its a quick transmigration? If so, do you remember any of the other arcs?
omg I feel like I remember it from one of the Quickly Transmigration novels. Its so familiar, I am going through every one of the Quickly Transmigration novel I read or am reading
If it's bl, maybe it's How To Die As Heavy As Mount Tai Or else, it may be just an original. I've read something similar to your description, I just don't know the title...
Taking over something or blackmailing people sound like something that Shi Sheng from Side Character Transmigrations: The Final Boss is No Joke will do...
Is it maybe a BL? Pleasing Start-Over has something very similar, but instead of zombie apocalypse, it's an interstellar ABO world (2nd arc, still being translated). and instead of scientist it's mecha engineers. Shou protagonist has a system and was constantly stealing the research information from MC's previous host and doesn't actually have the foundation for it. previous host was sabotaged by Shou protagonist and MC steps in to change what happens.
Maybe Sinister Ex Girlfriend? its a quick transmigration and they currently are on a zombie apocalypse arc