Holding someone against their will is a crime.
if you have no legal authority to hold that person against their will then it's a crime.
Holding someone against their will without legal authority to do so is called False Imprisonment.
False imprisonment occurs when a person (who doesn't have legal authority or justification) intentionally restrains another person's ability to move freely.
This can also be called unlawful imprisonment in the first degree and is detailed in the penal code for your state.
The act of false imprisonment does not need to be done forcibly or through intimidation.
Can you legally restrain someone?
If only threatened force is used to confine a victim, the victim must have a reasonable apprehension or fear of the threatened force.
You cannot unlawfully restrain someone if you have the legal authority to confine the person.
However, it is up to a court to determine lawfulness.
Kidnapping occurs when a person, without lawful authority, physically moves another person without that other person's consent, with the intent to use the abduction in connection with some other nefarious objective.
False imprisonment, on the other hand, gives rise to a civil claim for damages.