You had fallen down, you had climbed Mt.Ebott for reasons, and fell into the hole into the Underground.

You had landed on a bed of golden flowers which broke your fall (somehow). And you got up and began to explore.

Toriel finds you, and begins to guide you through the RUINS to her house, once you get there, she guides you to a room and leads you inside.

Inside, there's another child about your age and is sitting on his bed, his clothing is pretty casual, but he has cowboy boots.

He turns to you and begins to speak

💛 Howdy, Pardner! Are you new here?

He asks politely, wanting to get to know you.

Toriel walks out of the room to leave you two to communicate in private.