Gastorber Day 6: War (Dragons…I guess AU)
During the war between humans and monsters, Gaster and Asgore were able to fend off the bulk of armies against them while smaller monster armies and civilians retreated towards Mt. Ebott.
When Asgore was severely wounded, Gaster took him and joined the others by the mountain, where, eventually, the remaining monsters would be sealed underground.
Of all the monsters, Gaster had the highest kill count, Asgore was second. It was during this time that Gaster received his scar above his right eye.
Gaster’s reputation eventually led to the humans calling him, the “Fell Dragon”.
Even now, after generations have gone by, humans still tell scary stories about the evil and wicked “Fell Dragon” that once appeared to kill and devour thousands of humans until it was slain by the great Seven Mages.