Get username from previous def into another def with if statement

I have some code where I'd like to use the inputted username again in another def, but it doesn't generate anything. I get a username with the following code without issues (s_print is a slow print for reference):

def input_username():
    username = input()
    user = username
    s_print('Hello {}!'.format(user))
    return user

input_username()

Then I have a def a bit later on in the code with various if statements:

def options_input():
    if option == '1': etc.
    elif option == 'Bye':
        end_user = input_username()
        s_print('Goodbye {}!.'.format(end_user))
    else: etc.

options_input() 

I want to get the username inputted in def input_username to be reprinted in the def options_input elif option == 'Bye' but it just generates blank with no error code/message, like it's looping continuously through code. What is going wrong?