Influence to join mechanic

Hi Guys. Im very new to the forum but i really need some help as ive been leaning to use ue4 by slowly building a game i have in mind. I follow tutorials and use many of the things ive learnt and adapt them to my own needs.

Im stuck with a specific mechanic. ( When i say im stuck i mean i dont even know where to start.) I want one character to be able to influence another to join their group based on an influence level. This character then follows the main character and its mode can be set to different stances.

Any help or insight would be greatly apprechiated.