Trouble with a player that doesn't fit the party's roleplay style

So just a quick background on the problem.    I have a player in my group that really loves D&D  and is always the first person to confirm he will be present for our next session.  The issue we are having is,  he is much younger than many of our other group members and often fails to role play his character in a meaningful way.  Alot of the time his role play can become counter productive to story narrative or the other players goals.   I don't want to punish him or kick him from the group,  i just want to guide him in the right direction.  

I have created an item that i think might encourage better role play.    I am just looking for some feedback from other DMs that might have delt with a similar problem, and what you have done to help curb the chaos.  the Item I created is  https://www.dndbeyond.com/magic-items/11516786-emblem-of-divine-favor     it basically gives a smaller version of bardic to the player for acting in a way that is in line with his oath.   

You will need to be a tad more specific.  Everything a player does in dnd is roleplaying.

You roleplay a barbarian beheading a dragon. You roleplay a rogue picking a pocket. You roleplay a cleric praying for healing spells. You roleplay the social interactions with the city watch. You roleplay exploring a dungeon.

So you mean they wanna murderhobo every npc that the rest of the party wants to talk to?

i mean it in the broad sense.  In fight's during oneshots he has cast fireball because it was funny (to him) that he also hit other players.   In social interactions he would brake his characters alignment and steal from someone the party was trying to help.   Example:  the party had discovered that a towns mayor was in on a plot to steal goods from passing caravans.  He would feed information to the thieves guild about what goods where coming into town and where they where headed.  The party decided that they would break into the mayor's home while he was making his morning rounds to talk with several of the business owners in the town.  The player in question decided that he would create a distraction by stripping down to his birthday suit and run through the town naked as a distraction.      This kind of role play can be funny from time to time,  but with it happening all of the time, the other players are starting to get uncomfortable and frustrated  with some of the actions.    Like i said i don't what to remove him i just want to guide him.     The idea behind the item is to encourage him to play a bit more grounded.  but not punish him for the occasional goof.     

 I'm trying to read between the lines: he creates a lot of chaos, and you made him an object that incentives respecting their oath? 

If the player has any significant relationship with a DnD God, the god will not be happy if one of their clerics or monks is not following the oath. It may lead to losing all power that was given by that God. But for minor offenses, I think it's up to the DM, e.g. the PC might have nightmares of his God being really pissed, and for instance you could get inspired by a Coven of hags and apply similar effects to the nightmares aftermath.

It's also a known problem that Partys with several alignments (aka a mix of good and neutral or lawful and chaotic) tend to break apart, causing issues with running the table.

Our group has done a few premade adventures and a few oneshots together.   The player in question  has played with us through the last couple of oneshots.   But we have now started a campaign that has potential to last for a very long time.  Players have spent a lot of time working on their backgrounds, and i a lot of time weaving them together behind the scenes to connect them in meaningful ways.    His style of roleplay hasn't changed with characters or stories.   We are starting our 3rd session today and i want to try and keep the shananigans in check, and teach him (as a newer player) that sometimes players what to have serious moments that are meaningful. 

A. Actions have consequences.  Depending on the amount of shame they have, having the world react to that reputation mechanically might reign some of it in.  

B. Pivot away from alignments as a hard coded mechanical element, or push into it way harder.  Treat him as Evil for the purposes of spells, traps, barriers, etc.  Or replace the morality matrix, zero in on the most frequent tendencies, and make NPCs acutely aware of that behavior on display.  

C. If they're being an attention hog, you potentially run the risk of becoming a therapist.  Because something else is going on, and it might be deeper than a disregard for other players.   

So, when i dm, i tend to let the party always percieve when another player is about to wreck their plans. 

Player1: "i kill the merchant"

Me, as dm, to rest of party: "you all see Player1 reach for his sword."

Rest of party: Nooooo!  

Player2: i grab him and push him out of the store.

Player3. I help

Me, as dm, to player1: "before you can draw your sword, your party grabs you and push you out the store"

No grapple checks. No rolls.it just happens.

If a player is clearly wrecking the game, i announce it.to the party, and any thing the party does to stop it auto succeeds.

If its some spontaneous action clearly at odds with what the rest of the party is doing, and its done without discussion among the other players, just slow the action down so the party can intervene, and let it auto succeed.

If the party is duscussing what to do, and one player advocates chaos and thr rest advocate lawful good, i let them work it out in conversation. Disagreement here is fine.  The party votes, and lawful good wins, then if the chaotic player simply does whatever they were going to.do.anyway, as dm you can slow the actions down to let the party deal with it and let them auto succeed.

The player who tries to steal the loot for themselves? Everyone in the party auto succeeds on perception checks to see it. Let the party deal with it. If they decide the thief doesnt get any of this loot, announce the loot is divided that way. 

It starts to get fuzzy when everyone agrees to stealth their way in, and one player fails a stealth check, a guard spots them, and they choose to kill the guard quiclkly and quietly.  You cant take player agency away completely. Not everything is a party vote.

When things go south like this, you might allow some metagamijg among your players to let them sort it out. But sometimes things go south and kinetic solutions arent any more wrong than other options.

But when everyone agrees to stealth in and the chaotic player announces "fireball", give the party the means to intervene. They grab his hands and cover his mouth before he can complete the spell. Its not raw, but it will save the campaign.

If mr chaos has this happen enough, they will realize they arent going to get away with being chaotic anymore. At which point, they will find a way to work with the rest of the party and find something else to do that works with the campaign, or, they will quit.

If they say theyre going yo quit, point out its a game everyone is playing and tell them they are welcome to stay if they can find a way to play that works.within the party. But if not, let them go.

I have seen murderhobos destroy campaigns. Players stealing from other players cause they think its cute.  And the DMs that just let it happen are destroying their own hatd work. 

The thing is, you want the party to work together, so you want them to deal with the problem. As dm, you can slow down chaotic actions and let the party intervene.

If you start imposing rules on how a particular playser must behave, thats actually not how you want the game to proceed. Dnd is cooperative story telling. The party has to cooperate, and your job as dm is simply make sure one player doesnt overrule the party by taking unilateral action. 

I would also add that the DM doing carrot and stick stuff with one particular player, is my least favorite response. The party should cooperate with each other, whatever they agree on. And if rhe party chooses chaos, the dm should resolve the encounter with their chaos.

I recall early editions where a dm would mess with a paladin player because the player didnt do lawful good the way the dm thought lawful good should look like. Thats a really terrible outcome.

If the party is ok with it, the dm should roll with it.

Trying to fix a problem player through in-game mechanisms isn't a good plan. If your carrot doesn't work (and it won't; you're not addressing the root cause, whatever it may be), you'll be tempted to try a stick.

Talk to him. Discuss what he finds fun about the game, and brainstorm ways he can get his fun without stepping on everybody else's. Emphasize that it's a cooperative game, and players should make characters who want to work together.

Also, how young is "much younger"? 8? 15? 25? Your description reads to me like "bored and young".

It's okay to guide him gently: "Is that how a lawful good paladin would act? Is that in accordance with your tenets?" Gently reminding him that it's a roleplaying game and a world with consequences to his actions is likely to get him back on track.

And hey, if that doesn't work, then show him the consequence of running through town without clothes. People will refuse to engage. Word gets around. They're now the party with the stripping paladin, and it will negatively impact their interactions with others who won't take them, or at least him, to not punish the others, seriously.

I think the big factor here I haven't seen anyone mention yet is that you keep saying you're playing a series of one-shots. Your player may feel more free to engage in silly shenanigans and more juvenile humor because they're not playing in an environment where long term investment or ongoing consequences for their actions exist like on a more traditional long-form campaign. 

In my adult group of fairly seasoned dnd players, whenever we do a one shot, everyone takes that as basically their cue to put their silly hats on and roll joke characters, and role playing is basically all just for the bit. 

If you want more investment in the game from this player, maybe try a more long-form game for them to invest in, rather than just a series of disconnected one shots. 

I echo what some other people have said. I get what you're trying to do with the item, but I don't think it will work. This doesn't sound like something that can be solved with game mechanics. Mostly because it sounds like you've got a person problem, not a mechanics problem.  Also as someone else said, how old is "much younger"? That might be your problem right there. 

And fwiw, I do get why this is an issue. The stuff you're describing actively gets in the way of other people's fun. I.e. casting fireball to intentionally hit his party, antagonizing an NPC they're trying to help, etc.

Have you tried just talking to him? I would start by asking him questions about what he's trying to do at any given time. Ask what he wants to do or why, or mention that this action could be a problem for the party. See what he's thinking. There's always a chance you he does have a game or character he's trying to play, and you can adjust for it. That can definitely include just playing out the straightforward effects for his actions. 

From there, you might need to talk to him outside of the game. If his answer is just that it's just funny to ruin the group's plans or to blow them up with a fireball, that might need a more direct conversation. I wouldn't do that with an audience. Text or call and say what you said here. He's awesome to play with and you love his enthusiasm, but his fun can't come at the expense of everybody else's. Ask how you can help him RP and have fun without it coming at the group's expense. 

But yeah, idk. The item is a cool item in general. I'd totally play with that. But you might be trying to hide your problem behind the screen, when you might really need just an honest conversation.

Reading the original post, I think something skimmed over is this line.

The issue we are having is,  he is much younger than many of our other group members and ...

That just sounds like a maturity and/or life experience disconnect.   You  don't say how big of a difference this is and how old the player is, which is understandable.

Assuming this is the actual issue, you will probably need a talking to , and have several sessions of having the player stop and redo what there 1st thought was.  You will need a lot of OOC in game to correct/redo.

Basically talk with him one one one, and then n the group and probably have the player give a quick overview of what they want to do, get approved or disapproved to do that .

You can't fix immaturity and/or lack of life experience.  But the younger human can better adapt and change to match a group vice an older person trying to adapt to a younger situation.

I'll second all the people who say sit this player down and have a serious discussion, reminding them that this is a cooperative game, and one person whose version of fun is ruining the fun for everyone else is not going to fly. That's about as clear as you can get for guidance.

If they still don't get the message, kick them.