Her Personality: 

Frisk's personality is usually ambiguous, allowing the player to project any personality onto Frisk since they're very often speechless to them. However, the narration that describes Frisk's actions occasionally changes depending on their LOVE. Frisk speaks to NPCs throughout the game, especially when ACTing in encounters, but the exact dialogue is shown only when the game gives multiple dialogue options. NPCs' dialogue boxes display "..." to show that the NPC is listening to Frisk,[5] and some NPCs respond to questions that Frisk asks.[6]

Depending on their actions, players can interpret Frisk as merciful and kind, or merciless and violent. Some NPCs emphasize Frisk's kindness, understanding, and grace in the epilogue.[7] Frisk is obedient and only disallows player input when they follow someone else's instructions, such as when Sans tells them to hide behind the conveniently-shaped lamp.

Ref: https://www.youtube.com/watch?v=aDz_tcqPo0s&t=49s

Try To Imagine On What She Might Sound Like If It was from The Actual Game!🥧🌻