Fully Customizable Backgrounds (5e Variant Rule)
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D&D 5e's background feature, while it helps encourage roleplaying, has the unintended side effect of pigeonholing adventurers into similar archetypes. If you're the type of player that writes a backstory and character concept before ever touching a game mechanic, you may not find a suitable background. While there are rules for customizing backgrounds, the game requires you to either take a feature from another background or homebrew a feature yourself. That's a lot of work for a backstory, not to mention there's no guarantee of balance.
These rules are for fully customizable backgrounds. They allow you adapt a background for any character, without needing to homebrew something from scratch, all while ensuring it stays balanced with the "vanilla" backgrounds.
As part of your background, you are granted one or two items of your choice and a belt pouch containing 10 gp. The items must be things that does not have any mechanics attached to it, including weight and cost. The noble's scroll of pedigree, the guild artisan's letter of introduction, and the soldier's insignia of rank would be suitable choices for an item; a weapon would not. After that you are granted either an item or two with a small cost(usually less than 10 gp total) or a tool related to your background, and a set of clothes.
As part of your background, you may choose any two skills, as well as a total of two tools or languages to gain proficiency in. You may choose to gain a language and a tool if you want.
Personality Traits, Ideals, Bonds, and Flaws
Because these rules are aimed toward players that are unable to find a background for their character, it's assumed you already have an idea of your character's personality. Instead of choosing from lists, write a (brief!) summary of your character's traits, ideals, bonds, and flaws. This is for both for you and your DM; you're giving a picture of how your character will act during play, independent of your backstory.
If you have figured out an idea for your background, but are unsure of how to roleplay them, you can look at other backgrounds' characteristics, historical or other examples of the background in different settings, or come up with a few ideas by yourself or with the help of your DM.
Choose one of the features below. If you are unable to fit your background into one of these features, you may be granting yourself too many bonuses in your backstory.
Backing of an Organization
You are a member of or have backing from a reasonably powerful entity, such as a church, army, or guild. Your organization will do what it can to support you when requested, such as granting shelter in their buildings, sending agents to assist the party, or lobbying a local government. In turn, you are expected to carry out the wishes of your organization; a conscripted soldier might be called in to battle bandits without pay, a trader may need to pay dues as requested, a magician might be required to share details of their studies, and so on. Failure to support your organization will result in you getting kicked out. Your DM has authority to determine what benefits and demands your organization provides.
As a general rule, the greater the assistance you can expect from your organization, the greater the demands it puts on you. A small trading guild has less power than large guild, but the larger guild will likely require heavier dues. A rank-and-file grunt may have less pull than a special forces soldier, but the grunt is required to do much less dangerous assignments. A lowly priest may not have the influence of a god's chosen champion, but the champion will need to perform much greater acts in their god's name.
Your particular set of skills is always in demand. Whatever your line of work is, someone looking for your services is willing to provide lodging and food in exchange for your work. Your recommendation for others of your profession carries a good deal of weight, potentially letting you extend employment to your party. A musician may be able to play for their stay at a tavern, or a sailor may be able to secure passage on a ship. Your DM has authority to determine whether someone is willing (or able) to hire your services.
Only take this feature if your line of work has barriers to entry. Anyone can be a musician, but few can say they are a musician by trade. Anyone can be a soldier, but few can say they are an experienced mercenary. If your already employed as part of your backstory, consider taking the Backing of An Organization feature instead.
You have knowledge of something that most people of your land don't know. This knowledge is something of significant power, such as the identity of a king's assassin, the steps to contact the black market, or the chemical recipe for gunpowder. Obtaining this knowledge usually comes at a high cost, and thus normally cannot be acquired during play. If your knowledge is significantly dangerous, it may even make you a target! Your DM has authority over the effects of your knowledge on the world.
If your knowledge is tied to your line of work, consider taking the Steady Employment feature instead. If your knowledge involves the interacting with the world around you, consider taking the Experience feature instead. Take this feature if your knowledge is of significant weight to the world, and thus carries power.
You are a well-known figure. People may come up to you on the street and ask for an autograph, or flee in terror as you approach. Whatever your reputation, you can use your fame as leverage to secure favors from others. You might be able to secure a place to stay from a local, or drop your name in an effort to get out of a crime. You choose exactly what you are reputable for; your DM chooses how people perceive you. You might be known as a noble, causing certain peasants to defer to your wishes while some willingly defy your commands. Or you might be known as a hero, gaining favor with those that support your cause but gathering hate from your enemies. Or you might just be very dangerous, causing people to act with caution around you.
If your reputation is limited to your field of employment, consider taking the Steady Employment feature instead. Take this feature if it's reasonably likely a random stranger knows your name.
You have lived long enough in a certain environment, such as a city, ocean, or forest, that you can navigate it more easily than most, moving faster in cities, surviving off seafood, finding position by the stars, etc. Your experience also allows you to lead your allies, granting them the same benefits.
If your experience is in navigating a trade, consider taking the Steady Employment feature instead. Take this feature if you can fend for yourself in the world, and take others with you.