changing npc response

[Grundy]

i would search for my answer because im guessing it has been talked about before but i dont even know what to search for, so sorry if its already here and im missing me.

does anyone have any examples of how you would make an NPC's reply to hails different?

example:
1st hail: npc emotes "looks around to see if anyone is listening and whispers to you "Listen carefully, $name, I'm only going to tell you once. The guards in this city are corrupt, they will do anything for a few silvers. They allow our enemies to walk our streets for the right price. You need to find out who is leading them and if they refuse to change you must kill him." "
2nd hail: npc says "hello! good day! ehh... We never met before right? My name is Reslecus."
3rd hail and every hail after that: npc says "Hello, friend. How are you?"

im guessing you would use some kind of flag but does anyone have an example of how this would be done?