Frisk in Underfell is shown to be extremely kind and merciful, even to the most ruthless of Monsters, which eventually led to their redemption and the shattering of the barrier with the help of Asriel. She is shown to get rather tired at times. She is a bit of a sensitive child sometimes, and can be rather timid and shy. Despite being shy, she does have a lot of Determination to press onward, no matter the circumstances.