You don’t necessarily need to roleplay, but something like “I would like to play on their guilt by seeming hopeless.” or “I would like to bring up the horrible acts of the orc warlord to stoke their anger.” or “I would like to convince them to help by pointing out how their oaths may apply in this situation.” would really help sell the specifics. If you are just trying a flat check I have no real way to know what you are planning on doing other than just sort of charmingly asking “Please?”