The Negotiator
Don’t let the fighter who used Charisma as their dump stat take the lead in talking to, well, anyone.
Some fighter archetypes seem like they should be good at persuasion, such as knights trained in courtly etiquette, or even gladiators who know how to win a crowd. This isn’t always well represented in the game; with few mechanical incentives to bump their social skills, many fighters happily leave Charisma as a single digit. This can have consequences. Especially if they’re the one who starts talking with the NPC.
I’ve been told (although never tried at my table) that the variant rules for Honor make an excellent mechanic alternative to the charismatic knight. They may not like your battle-scarred face, but with the number of honorable battles fought none may question the intent behind your actions.