So we just started a new campaign with new characters. Two of the characters aren't afraid to get their hands dirty to get what they want. In the very first session the one character, who plays a homebrewed Yeti race roared at another player to intimidate them so they would scram. With most social interactions there's a contested roll to see how it effects the other person. But the problem we had is we had no idea which skill to use. So which skill should be used to contest the intimidation?
One of us is leaning more towards pure charisma while another is leaning towards insight. Would this actually be an intimidation roll or should they just purely roleplay it out? But then if it was a NPC instead, what would the NPC roll for? They tried interrogating one previously and intimidating them and rolled really high to get info from them. However, I, as the DM, didn't want them to know any info and played the NPC as someone who would rather die than spill any information.