DnD 5e - Social Interaction
Social Interaction is arguably the most complicated part of a roleplaying game, but the entirety of the Social Interaction rules amounts to a single page of text in Player's Handbook. Social interaction in roleplaying games is complicated because social interaction in the real world is complicated, and you must add the additional complications of inhabiting a character whose personality, life experience, culture, and mannerisms might be totally different from your own, and you may find yourself interacting with characters as relatable as a local merchant or as foreign and fantastic as a deity.
Social interaction has two components: Roleplaying and Ability Checks. Roleplaying involves acting and dictating your characters words and actions. Ability checks involve rolling dice based on your roleplaying to determine the outcome of your roleplaying.
Non-Player Characters (NPCs)
Players control their own characters (Player Characters, or PCs), while the Dungeon Master controls all other characters (Non-Player Characters, or NPCs).
While an NPC might have a complicated set of opinions about another character, their general attitude can be sorted into three broad categories: Friendly, Indifferent, or Hostile. Friendly creatures are likely to help you and treat you kindly. Indifferent creatures might like you, but not enough to go out of their way to help you. Similarly, they might dislike you a great deal, but won't go out of their way to cause trouble for you. Hostile creatures actively seek to hinder or even harm you. Just like real life, your words and actions can affect a character's attitude toward you.
Social interaction shares a lot in common with improvisational acting. You play your own character, and do your best to act and respond in a way that your character would act. This is perhaps the truest form of roleplaying, in that you are acting out the role of your character. If you have any experience acting, this may feel familiar and comfortable, but if you don't you can still be a great roleplayer.
As with other parts of the game, roleplaying can be performed in 1st-person or in 3rd-person as you prefer. For more on this, see What is a Roleplaying Game, earlier in this guide.
Ability checks are an important part of roleplaying for two reasons: first, it keeps the game impartial, allowing the DM to determine the behavior of NPCs based on an impartial result rather than solely on how roleplaying went between two real-world people with all of the associated real-world complications. Remember: the DM is intended to be an impartial arbiter of the rules, and their own moods and feelings might conflict with what a NPC would normally say or do.
Second, ability checks allow real-world people who might not be able to match their character's capabilities to still portray their characters capabilities in the game. For example: If you're quick-witted and charming, but you're playing an oafish barbarian with terrible Intelligence and Charisma, it's easy to bring your real-world talents into roleplaying, but ability checks turn your character's limited social graces into an effective limiter on your own skills. Conversely, if you're no social butterfly, but you're playing a silver-tongued sorcerer with a mountain of Charisma, ability checks allow your character to talk their way through situations while you might be struggling to form coherent sentences in the real world.
The majority of ability checks performed during social interaction are Charisma checks, which makes sense because Charisma indicates a character's social skills. However, other ability checks are absolutely possible. You might use Intelligence (Arcana) to befriend a wizard or a scholar by discussing some bit of esoterica, or you might use Wisdom (Animal Handling) to build raport with a shepherd. Look for opportunities to bring your character's strengths into an interaction, and even characters with awful Charisma can contribute meaningfully in social situations.
In some cases, groups choose to forgo ability checks during roleplaying. This requires a great deal of comfort with roleplaying and a great deal of trust between everyone at the table, and even then not every group chooses to play this way. I've been playing roleplaying games for nearly 20 years and I like to think that I'm a good roleplayer, but I still prefer to use ability checks because I simply can't portray charismatic characters as well as I would like without a great deal of rehearsal that simply isn't possible at the table. If you never get to the point that you're comfortable roleplaying without dice, that is perfectly fine. The decision to roleplay without ability checks is a stylistic choice; it is not an indicator of proficiency.
Roleplaying with Other PCs
While a great deal of roleplaying occurs between PCs and NPCs, roleplaying also occurs between PCs. When this occurs, some amount of real-world ettiquette is required, and using ability checks may become complicated, as leaving the outcome of an interaction between players up to the outcome of a dice roll can lead to hurt feelings, real-world disagreements, and generally less fun all around.
When your character interacts with another PC, be respectful of the other player. Always be mindful of player agency (the player's ability to dictate their own character's thoughts, feelings, and actions unimpeded), and at no point should you dictate how another PC should respond to your own words and actions. Even if you disagree with how another player portrays their character. They might be acting one some aspect of the character which you're simply not aware of, or any number of other factors might cause the other player to respond in a way you didn't expect. Similarly, you should expect the same respect from other players.
You should also be aware of the consequences of your character's words and actions. The other characters are rarely under any obligation to keep your character around, and when you're going into life-or-death situations you typically don't want to do so alongside people who you dislike or distrust. Many players have made the mistake of playing a character who doesn't fit into a party: a loner; a character who is beligerent, racist, or otherwise hostile to other members of the party; a character who steals from or otherwise actively harms other members of the party; or any number of other characters who the party would otherwise consider antagonistic. If you intend to play one of those sorts of characters, discuss it with your group before you make the character and find ways to integrate the character into the party which justify the rest of the party continuing to associate with you.
In some cases, you may still choose to use ability checks when interacting with other PCs. If done right, this can lead to exciting, unexpected outcomes which can feel very rewarding. However, if either player isn't totally comfortable with the outcome it can cause long-term problems. I recommend doing this on a case-by-case basis, and both players should agree to the decision before dice are rolled, and they should agree on the possible outcomes of the roll before it is made.
For example: Phil the Paladin and Red the Rogue have captured their foe, the evil Count Villainname. Red wants to kill the Count on the spot to get vengeance for his dead family, knowing that delaying would give the Count's allies to free him from the heroes and enable him to continue his reign of terror and violence. Phil wants to take the Count captive and try him publicly for his numerous crimes to begin repairing decades of problems created by the Count's malfeasance, knowing full well that it will bring them into conflict with the Count's powerful allies. The two players roleplay an emotional debate carried out between the two characters, and while both of their reasons are valid, neither is willing to let the other have their way and they are unable to find a compromise. One of the players proposes leaving the outcome to an ability check. They decide on the nature of the check (an opposed Charisma (Persuasion) check), and agree that the winner will decide the Count's fate, and in the event of a tie the characters are unable to decide and postpone the decision until the rest of the party can weigh in. Both players roll, the decision is made, and the game continues.