When you agree with someone in the negative you can use not either or neither.
For example B agrees with A in the negative:-
A: I don't like cheese.
If you don't like cheese, you can show your agreement in different ways:-
B: I don't like it either. / Neither do I. / Me neither.
A: I didn't enjoy the film.
And here's one for Joao.
Me: I am never alone.
See also either / as well / too
See also either or vs neither nor