This has been asked a 100 different ways and I’m not quite finding the inspiration I need… So let me try a 101th way.  Im kicking off a new campaign with 5 PCs starting at lvl6.  One PC wants to play a multiclass Rogue/Bard of sneaking, thieving and gaining surprise.   For example, when the group traveled down and road the PC stated that they moved along the brush/trees the entire way so to always be hidden.  While the group enters shops, the PC would stay outside and try to pick locks and steal items from the back of the shop.  This PC is working with a +9 stealth and has advantage on all stealth checks and those trying to perceive him have disadvantage.

Here is where my questions differs a little…  How do I allow this PC to do this and make it challenging/fun enough for them to enjoy their character’s design while maintaining the integrity of the campaign long term for the group?  As a DM, I don’t want to tell a PC they CAN’T do something (especially if it is the one thing they are designed to do) if anything, I want to reward players for using their characters as design and coming up with unique solutions to situations but… I do want to sense of risk/reward and have impact to all PC actions to keep the suspense in the game.

Another consideration is balancing the admin and pace of the game.  Requiring checks for every stealthy move gets old but just allowing/disallowing attempts tend to pit PCs and the DM against each other.

Any recommendations on sourcebook material to read up on or forums to check out to think through this?

I have no suggestion as that’s a PC type I strongly discourage. A D&D party is a team and the player wants to play a character who is not a team player. 

That's not to say I forbid sneaky characters. I allow ones who use their abilities situationally to help the team. So they'll sneak to scout ahead in a dangerous situation, or pick locks on barriers and help disable traps.

Let them play their character as they wish and allow the pieces to fall where they may.  If the other PCs get tired of it they'll make it known in character that they don't want the character always crouching and sneaking when they go everywhere.

More over remember that you have the power of the gods at your disposal.  You may need to show the PC once or twice that a high stealth score is not a get out of jail free card to do whatever they want.  All it takes is a town guard or two with a +10 to Perception to suddenly catch them in their sneaking attempt and that will help allow the Player to realize their character is not an omnipotent shadow.

Stealthing along the road -- the party is OK with this? He's making them move at reduced speed, no? Do they mind creeping along the road at slow speeds just so shadow-boy can feel all stealthy and sneaky? Also, why was it possible to "always be hidden?" He can hide in bushes, sure, but bushes do not grow continuously. Once he moves across an exposed area, stealth is not possible. You should not allow players a "chance" to do the logically impossible. If it's absurd (like walking across a field of open ankle-high grass without cover and trying to "stealth"), don't even let him roll.

Why do all the shops have back doors? Why are all the shop back doors locked with a pickable lock instead of say, a bar across the inside, which cannot be picked? If there's no door, or if the door is not locked from the outside, he cannot pick the lock. I mean, some shops might have a padlocked back door, but not all. He shouldn't be able to just do this at will on the basis of simple realism and world logic. Also, why are the shops all positioned so that nobody is going to notice him making his lockpick attempt?

Stealth -- means that you can "hide in the shadows." Stealth is not "silence + invisibility." Those are spells. Spells are not stealth. Stealth will not let him go unnoticed down the middle of a street in broad daylight. Or stand on the clearly visible, unshaded, back stoop of a shop in plain site of every back window of every house on the block and not be seen. NPCs don't have to make a "perception check" for that. Only if it's possible he could actually hide, which I don't care if he has +9 or +90, you cannot do in broad daylight out in the open.

Also, is the party aware of it and do they approve/condone his actions? If not, why are they sitting by allowing it? Why isn't the Paladin tapping him on the shoulder while he's picking the shop's back lock and demanding to know what the bleep he is doing?

A lot of this just sounds metagamey and ridiculous, and I would put a stop to it. I prefer having a talk with the player. Explain that he is harming the pace of the game... that stealth is not intended to be used on a constant basis 24/7, and that his character will have plenty of chances to shine without doing these things constantly. You could try dealing with it in-character, but in my experience this is not usually a good idea. He doesn't sound like he's being particularly fussy about the IC-ness of the situation (instead he's being the opposite) and so he won't care if there are IC implications.

How is it that this PC has permanent advantage on stealth checks (and that observers have permanent disadvantage)?

So, some practical advice. For the sneaking while traveling, an action done continuously can use 10+ skill value as a passive value. Though he will fall behind the rest of the party as they won’t know where he is, so really can’t reduce their speed to match.

Perhaps suggest to him that instead if something is coming up on their travels you decide if you’ll give him an opportunity to choose to hide. Obviously if it’s something he has no opportunity to anticipate he doesn’t get the hide chance, but can do so once the encounter starts. 

As for breaking into and stealing from stores, you should shut that down. If it’s a place the party frequents perhaps the owner notices things go missing every time they visit, so refuses service. Merchants look out for each other, so word will get around and they’ll be blacklisted.  You could also set up a store that has valuable stuff but is properly guarded against sneaky characters. Maybe some creature or magic?

You'd think by now (it is 2020, right?) everyone would know "don't split the party." :-)

Use a spotlight (the spotlight being the GM's time)

Each player at the table should get roughly the same amount of time in the spotlight. Usually the spotlight is on the whole team, so everyone shares the time. If the party is split, the GM should allocate time proportionally. If there are five players and one splits off, then for every 10 minutes the GM spends on the one player, they spend 40 minutes on the other players (though it doesn't have to be consecutive). During the 40 minutes, the one player is not allowed to talk. After all, their character is not there.

Consequences

If the rogue is round the back of the store then they are not interacting with the shopkeeper. If the merchant says "I have leather armour on special", the rogue's can't say, "I'll get that." If they haven't given the other characters a shopping list then they don't buy anything. If the merchant gives the party a discount for services done, the rogue doesn't get it. After all, as far as the merchant knows, the rogue is not part of the party.

If the rogue is off on a solo trip when the team finishes a mission for the noble who hired them, then the rogue doesn't get any of the rewards. No reputation, no favours owed. After all, the noble never saw the rogue.

If the rogue is not with the party then they can't take part in party combat. The players of the other characters will notice when they fight every combat at 4/5 strength.

If the rogue is spending all day sneaking around the woods a long way from the rest of the party then the rogue's player can't take part in any conversation. There's also the issue of how they find the rest of the party for evening camp after spending 8 hours with no idea of their position or speed.

It works the other way - if the rogue is caught by the guard when being criminal then the party can't help. In fact, the party might not even know the rogue has been caught and is languishing in a cell.

GM Fiat

The GM can always say, "No. This is a team game. If your character is not a team player then retire them and create an new one who is. If you want to play a solo game, that's what Baldur's Gate and Beyond Divinity are for."

Summary

Don't punish the player, but make sure you let them know this is a team game and if they are not a team member then there will be consequences.

Sneaking along the road: make it impractical as a lot of people have said before. If necessary, make time an issue, then the player has to decide wether he/she wants to be there in time for what happens, or be sneaking along the road while the rest of the party face of some bad guy.

But a side note: people constantly sneaking, checking traps etc. Just make sure it isn't because you keep surprising them with ambushes and stuff. If the player(s) have the feeling that unless they are sneaking ALL the time, they will be ambushed, try to do something with that. Allow some perception rolls, give them a hint that this part of the travel seems dangerous.

As for breaking into stores. As said by someone else, not every shop has a backdoor, and you set the DC. Make it difficult. If he fails to pick lock, have someone notice him, make it difficult for him.

But the best advice is possibly to talk with him. Like others have pointed out, the real problem isn't that he steals from stores, it is that he steals time from the other players.

Quote from cpedroson >>

This has been asked a 100 different ways and I’m not quite finding the inspiration I need… So let me try a 101th way.  Im kicking off a new campaign with 5 PCs starting at lvl6.  One PC wants to play a multiclass Rogue/Bard of sneaking, thieving and gaining surprise.   For example, when the group traveled down and road the PC stated that they moved along the brush/trees the entire way so to always be hidden.  While the group enters shops, the PC would stay outside and try to pick locks and steal items from the back of the shop.  This PC is working with a +9 stealth and has advantage on all stealth checks and those trying to perceive him have disadvantage.

 

Here is where my questions differs a little…  How do I allow this PC to do this and make it challenging/fun enough for them to enjoy their character’s design while maintaining the integrity of the campaign long term for the group?  As a DM, I don’t want to tell a PC they CAN’T do something (especially if it is the one thing they are designed to do) if anything, I want to reward players for using their characters as design and coming up with unique solutions to situations but… I do want to sense of risk/reward and have impact to all PC actions to keep the suspense in the game.

 

Another consideration is balancing the admin and pace of the game.  Requiring checks for every stealthy move gets old but just allowing/disallowing attempts tend to pit PCs and the DM against each other.

 

Any recommendations on sourcebook material to read up on or forums to check out to think through this?

 The shop thing. Repercussions as the group is accomplice to robbery.

the traveling down the path. Perfectly fine and legit. But they would have separate perception rolls as to the rest of the group. And depending on the terrain, might even fall behind.

-What kind of shop doesn’t have “alarm” spell set up on the back doors? 

I would say that someone expending all the energy to be stealthy all that time would face a level of exertion that if maintained would possibly cause exhaustion.

Just a thought....

I would say that there is a difference between players and their characters as well as trying to do something and being able to do something. I wouldn't tell a player they couldn't try make an arcana check to have their character learn fly on the fly, after they decided to jump off a castle turret. However I am not required to give them a 5% (20 on a d20) or better chance to succeed. Nor do I think that trying to pick the backdoor of every shop or always hide in the bushes on the side of the road are unique or creative solutions, and as others have noted there are multiple ways to mitigate this problem. That being said, don't forget the proverbial carrot; build significant encounters in which stealth is important and they get to shine. Make it interesting and important and the player may not care as much about trying to use it in every circumstance.

Edit: proofreading (or postreading)

Assuming the player has no ill-will and just wants to hang out and play DnD, and thinks ninjas are cool, or realized that the other classes/roles they were interested were taken: have an out of game conversation with them about the fact that they will have chances to shine, and then make sure they get those chances. I think it could create a negative feedback loop if this player thinks they’re using the cool aspects of their character only to have you actively try to thwart their plans. They’ll pick up on it, likely perceive it as you singling them out, and then be upset because the wizard gets to do wizard stuff, the fighter does fighter stuff, but they don’t get their own time to shine. So make sure you build in some traps to disarm, enemy strongholds to break into, guards to assassinate, and rude rich people to pickpocket. Then they won’t be obsessed with trying to break into every house and raid the cupboard like it’s a video game.

Possibility Two, they realize they’re making the game less fun for everyone but don’t care, and actively enjoy being edgy and disruptive: give them one warning and opportunity to play with the group, otherwise they’re no longer playing DnD at your table.

Increase the DC on his checks and/or have him pick a cursed item ..

Don't leave out the possibility of a shop having wards, arcane locks, and/or arcane traps.  The rogue would not, necessarily, have the skill-set to find or overcome magical locks and traps.

Also, the law is not blind, deaf, and dumb. If there is a rash of thefts (especially in certain neighborhoods), the constabulary could pose a threat to the character.  Additionally, if he/she gets captured, it could lead to further stories for that character... but he/she is out of the party, unless excused of the crime.  In such a  case, the player should roll another character and save the current one for other games.