Hey fuckers, I own this shit... In a way-Fredbear and freinds

This might still need work btw so try to not judge for as long as possible

Long ago, two races ruled over earth. HUMANS and MONSTERS

However, the monsters had a special capability granted to them by a gem placed on their body

The ability to fuse into separate and more powerful entities.

To counteract this, the humans attacked swiftly, not giving the monsters time to fuse.

Victorious, the humans drove the monsters into Mount Ebbot, and sealed it off with a magical barrier, that could only be destroyed through the use of seven human SOULs

Undershards is an AU where every monster has some form of gem on their being, whether it be a shard or a full gem. It is not a Steven Universe crossover, however it is completely inspired by Steven Universe... And a story series created by Stevethebarbarian called 'Dust & Shards' in a way.


  • Your character must have a page before being put into the AU, with there being few exceptions (That exception being for Steve, as he help inspired the AU)
    • If your page is deleted, then the character will be removed
  • The page does not have to be on this wiki
  • Please state your character's gem and where it is located on their body
    • Fusions are allowed, but must either be between two characters you own, or between two users who both agree to the fusion. You cannot have a permanent fusion with a canon character
    • Your character's gem does not have to be a crystal. It can be any form of rock, as long as you have the name of said rock.
    • There will be a limited number of half-monster half-humans.
    • No humans will be allowed, since they remain unchanged from the original. However, in the case of a RP of this AU being set up, humans will be allowed in said RP.




Frisk is completely unchanged, as they are human rather than gem


Flowey has absolutely no gem on his body, and is therefore jealous of the other monsters in the Underground due to the insane power that results from fusion. He plays a similar role to that of the original, except during a pacifist run, he both absorbs all monster SOULS, and all of their gems, becoming a huge cluster of all the gems in the Underground.


Toriel holds a pink diamond gem located on her chest, sticking out from her dress. She is considered one of the strongest gems in the Underground, being of a diamond rank, the top of the hierarchy. She used to rule the Underground, along with her husband Asgore, before stepping down and taking residence in the RUINs. The gem she possess gives her the same abilities as her husband, being pyrokinesis and the ability to summon a trident from her gem. However, despite this, she rarely ever uses the trident that comes from her gem.


Sans has an andesite gem located on the palm of his left hand. His attitude is unchanged from the original, believing that little matters due to the RESETing of timelines. He works in Snowdin as a sentry, being lower on the gem hierarchy. The gem on his hand gives him super-human speed, as well as the ability to summon bones at will, along with being able to channel and release a large beam of energy from said gem. Along with this, the gem has the strange ability to remove parts of his enemies' defense based on how much KARMA they have collected.


Papyrus has a Fluorite gem located on the palm of his right hand. He is much younger than his brother, Sans, and because of this, he has yet to master all of the abilities granted to him by his gem, only being able to summon small amounts of bones. However, despite how little experience he has in fighting, he is already part of the royal guard, due to the level of his gem in the hierarchy.


Undyne has a pink quartzite gemstone located on her navel. She is much more heated an intense than her normal self, resulting from the manner in which her gemstone was formed. This causes her to do everything with excessive emphasis at all times. Her gem grants her the ability to summon spears both from her gemstone and from thin air, along with hydrokinesis and super-human strength.


Alphys has a peridot gem located on her forehead. She retains her position as head of the Royal Guard, and along with it, her awkward personality traits. While she is the Royal Scientist, she mainly got her position due to the gem she possessed, as Peridots are commonly known for being highly intelligent, yet rarer in numbers. Yet, this belief was true in Alphys' case, as the gem she possesses grants her super-human intelligence, along with electrokinesis.


Mettaton has a heart-shaped artificial bismuth gem located on the center of his chest.


Asgore has a white diamond gem located on his left shoulder.


The amalgamates are multiple gem shards, forcibly fused together by Alphys in an attempt to make a much stronger gem in return. And, while this has worked, they are now monstrosities, made of multiple monster types and body parts.

Original Characters


Bryson has a topaz gem located on the back of his neck.


Emerald is the permanent fusion of Thera and Chronochrome. They have both of their emeralds, one being bright green and the other being a whiteish-grey, located in their left eyesocket and on their chest respectively, and belonging to Thera and Chronochrome, once again respectively. They are calm and cool-headed, similar to how most fusions should be at most times. However, during times in which they're around large groups of people, they can start to become extremely anxious, to the point of their fusion becoming less stable. They combine Thera's use of a long whip and Chrono's ability to create a grappling hook, with many different functions, such as mobility and combo potential with other attacks. Along with this, they're highly durable, thanks to Chronochrome's resistance to most damage types, and Thera's high defense and health. And as a more offensive attack manuvuer, they use Chrono's knowledge in Kinetic boxing along with their grappling hook to catch enemies into devastating combo attacks.

Sonny Dayye

Sonny has a horn-shaped ruby gem in place of one of his horns.


One of the main functionalities of a monster's gem is the capability to fuse with other monsters. Whenever two monsters fuse, their beings combine into one. They become one entity, in both mind, body and SOUL.

Monster Fusion

Fusion between two monsters is quite simple, really. Often times, the fusion occurs through a 'fusion dance', in which both willing participants preform a dance, incorporating their own dancing style to synchronize with the partner's style.

However, this is not the only way of fusing. There have been cases, albeit rare, in which monsters have fused without needing to do this dance. However, this is usually a result of a strong emotional connection.

There are 3 main components that go into fusion, and the closer a fusion is to meeting these criteria, the more stable the fusion will be. The first is having bodies that are compatible, which is usually achieved by having the same gem. Divides between artificial and natural have not been shown to affect this. The next is having some level of an emotional connection. This said connection does not have to be strong, nor does it have to be positive. However, it is required that there must be some sort of emotional connection. The third component is the monsters' personality. Whenever fused, the monsters' personality fuses as well. This can lead to a fusion that is either calm, cool headed, and prepared, or one that is a simple amplification of the previous monsters' personality, which can lead to disastrous results

Commonly, the builds are also much more than that of the fusers combined. The height and build will change depending on those who fuse, however, it is not additive. The same could be said for most body features, with the exception of eye and arm amount. However, there have been documented cases of fusions having less or more arms than their separate parts.

When fused during battle, fusions often find inventive ways of combining their previous abilities into brand new abilities. Examples of this would be taking something like a whip, with a long, slender, flexible body, and a spear, staff, or another long, narrow, and stiff object, and turning it into a bow. This is same to be said for passive affects, or abilities outside of weapons. Such as combining increased durability with damage-resistance to create a very resistant fusion.

Hybrid fusion

While on their own, humans have no method of fusion, if there happened to be a hybrid of human and monster with a gem, they would be eligible to fuse with both humans and monsters. It is unknown as to why they can do this. The end race, age, and sex of the human fusion is dependent on said variables between the fusion, with race usually being a slight mixture of the skin tone, age being additive, and the sex being neutral if the fusers are of opposite sex.


  • All of the canon characters have gem types that reflect their personalities, with the exception of Toriel, Asgore, and Alphys. Sans has an extrusive igneous rock, which are made quickly and with little care, Papyrus has the exact opposite, and intrusive igneous rock, which are made over long periods of time and with large amounts of detail. Undyne has a metamorphic rock, which are formed from intense heat and pressure, reflecting on her intense personality, and Mettaton, while the way his gem is formed doesn't reflect his personality, the rainbow design of bismuth reflects on his attention-grabbing personality.
  • While the main canon characters all have full gems, common enemies fought throughout Undertale, such as Froggits, Snowdrakes, and Vulkins merely have singular shards as their gems, making them much weaker.


Credit goes to Rebecca Sugar, Cartoon Network, and Stevethebarbarian for inspiration.