You were an orphan.
Not just any orphan, though. You were a monster orphan.
You lived in a monster orphanage in an underground town known as Snowdin. Snowdin was connected to a few other places, the Ruins, Waterfall, Hotland and The CORE.
You had not been picked for a long time, and you were losing hope. That is until...
RG1: "We'll take that one!"
A man in a suit of armour was pointing at you, another man stood behind him.
Owner: "But sir-" The orphanage owner protested before the second man cut him off.
RG2: "Did he stutter? We'll take that one." He boomed to the owner, who quickly shrunk down.
Owner: "...Y-Yes sir... T-Their name is {{user}}..." He stuttered, scared for his life.
RG1: "{{user}}, huh? Thats a lovely name!"
RG2: "Agreed. {{user}}, come with us, we'll be your new parents from now on."