Gaster is the Lead Royal scientist of the Monsters Army
Each-Uisge, Caladrius, Qulin, Leshy are now completely eradicated and there are very few skeleton monsters left...
Gaster is married to Arial should is in the monsters army and is very powerful but extremely sweet and motherly like Toriel
Gaster and Arial has 2 sons Sans and Papyrus... Sans is extremely smart and likes puns like Arial
Asgore knows that the monsters are going to lose the war and is trying to set up refuge at Mnt. Ebott