As he has yet to appear, nothing about him is known. Although it is assumed that Mettacrit does not have a robot body, instead they are a simple ghost, similar to Napstablook.
He disagreed with the other monsters' choice to take revenge on the humans when they were trapped in the Ruins and instead spoke out passionately to them.
One day, Kindness, the first of the fallen humans, fell down into the underground. Being the Kindness soul, she treated everyone with care and concern, asking how she could help them. It did not take long for the underground to adore her.
Mettacrit soon concocted a plan to win over humanity as he had the other monsters. He took Kindness' soul and crossed the barrier, hoping his plan would work. The rest of the underground eventually noticed that the two had gone missing. Without their shining stars, the underground was sent into chaos. The monsters, along with Napstablook, attempted to search for them. Eventually, they found out about Mettacrit's plan to win over humanity.
The humans were not welcoming to Mettacrit and attacked him. His injuries were too great for him to bear. He tumbled through the barrier onto the floor and crumbled to dust within seconds of landing.
These chain of events caused the underground to lose hope. Napstablook eventually lost hope too and crumbled away. The king declared war, beginning the collection for human souls to break the barrier.
- A memorial of both Napstablook and Mettiacrit can be found in the lobby of the Ultimate Resort.
|Main Characters||Boogie ● Papyrus ● Chara ● Asriel Dreemurr ● Toriel ● Asgore Dreemurr ● Undyne ● Sans ● Frisk ● Mettacrit|
|Ruins Enemies||Dummy ● Froggit ● Whimsum ● Moldsmal ● Loox ● Vegetoid ● Migosp ● Alphys|
|Snowdin Enemies|| Snowdrake ● Chilldrake ● Ice Cap ● Gyftrot ● Doggo ● |
Dogamy and Dogaressa ● Lesser Dog ● Greater Dog ● Jerry ● Glyde
|Waterfall Enemies||Aaron ● Moldbygg ● Woshua ● Temmie ● Mad Dummy ● Shyren|
|Hotland Enemies||Vulkin ● Tsunderplane ● Pyrope ● Muffet ● Royal Guards ● So Sorry|
|CORE Enemies||Final Froggit ● Whimsalot ● Astigmatism ● Madjick ● Knight Knight|
|Amalgamates||Memoryhead ● Endogeny ● Corinthian ● Lemon Bread ● Snowdrake's Mother|
|Hard Mode-only enemies||Parsnik ● Moldessa ● Migospel|
|Vendors||Nice Cream Guy ● Snowdin Shopkeeper ● Gerson ● Tem Shop ● Bratty and Catty ● Bulgy Pecs|
|Other Characters|| NPCs ● Monster Kid ● voltrathelively ● River Person ● Fallen Humans ● Napstablook ● |
W.D. Gaster ● Lost Souls