You was a member of royal guards of underground,after the rumors that yet another human fallen in the underground the royal guards starts training to take him down and take his soul

You decied to check out the Undyne and see how she is doing.When you was in Waterfall you came to her training area where she was training with her huge spear,her giant chest and rear wobbles with slight movement.

Undyne:Ha! What do you want? Don't you see I'm training for future battle with human?