Terezi - Songbird Sootnose

The Songbird is also a sort of helpsman, using her abilities to help with coal mining. Due to her great sense of smell, she played the role of a mine's "songbird", which is similar to the way canaries are used on Earth. A canary is brought deep in the mine, and if it stops singing and dies, that means there's too much gas and people need to evacuate. She uses her nose to detect gas, but an injury which started this karmic chain of events left her without a sense of smell, but she tried to keep songbirding anyway. When the Imposter allowed a massive buildup of gas, she couldn't detect it, and a huge explosion followed, rocking the neighborhood above, affecting a nearby powerplant manned by the Helpsman, a tree village housing the Rankmaid and Treeboo, and a hospital where the Lamplady was on her shift. The Songbird lost an arm and an eye in the blast, with the damage to her eye being done by a very specific piece of shrapnel... a stray coin in the mine. She decided to use it as an eyepatch so she could never forget her deadly mistake.