Frisk Brewers-Dreemurr

Underground
The adopted daughter of Asgore and Toriel, Frisk turns 16 in the opening episode of Voxistale, and remains 16 to the current point in the story. She's wise beyond her years, but still suffers from the great crippling disease of hormones. She's evolved into a more emotional and sensitive character from her time Underground (during which she was 12). After countless timelines, passive or otherwise, she eventually gave up and decided to remain underground indefinitely until the CORE began to destabilize, prompting the magma to rise. The underground was evacuated. Flowey, using the six human SOULs, attempted to break the barrier, but couldn't until Frisk added her own SOUL to the mix. The barrier was shattered, but the six human SOULs were lost, and Frisk barely survived, losing a great deal of her powers, including control of the timeline. She reveals this a short time after the eruption of Mt. Ebott to Flowey and Sans, the latter of which is satisfied with this outcome.

The Surface
As the acting ambassador for monsterkind, Frisk took her duties seriously until Asgore assumed responsibility so that Frisk could focus on school, friends, and anything else. During her time at Voxis Middle School, Frisk met and befriended Terrence Anoma and Gregory Favian. When she was 14, she and Terrence started dating. The relationship only lasted a month before the two broke up, but remained friends.

Episode 1 "A Happy Ending"
The episode opens on Frisk's 16th birthday as she worked on an English assignment she'd been procrastinating on until Toriel called her down for breakfast. There, Frisk ate her birthday breakfast before Sans took her to school, during which Frisk reflects on Toriel's new, mysterious nature, clearly hiding something. Once at school, Frisk attends Marine Biology with Gregory, and she discusses that she saw a mysterious figure again, as for some amount of time she's been seeing somebody watching her house from outside. They later discuss this with Terrence, who suggests she tell Toriel. Frisk agrees.

For her birthday, the three decide to go to Grillby's. There, they discuss Fuku Fire, Grillby's daughter. Terrence and Greg conflict over what to do for Frisk's birthday, as Gregory doesn't want to miss school and Terrence wants to go to the mall. Frisk eventually ended the conflict by stating they could go some other time. The trio ate at Grillby's before returning to school, Frisk questioning Terrence's lack of effort in his homework, alluding to his less than ideal home life.

After school, Sans provided Frisk a ride home, the two discussing Toriel's current absence as she hadn't returned home, which greatly upset Frisk, who was beginning to feel as though her adopted mother was beginning to care less about her. Sans offered Frisk to hang out at his place, which she denied. He dropped her off at her house, finding birthday letters and a note from Toriel. Annoyed that Toriel wasn't there in person, she threw away the note and went to her room upstairs, finding another note that she crumpled and tossed aside before passing out on her bed. When she woke, she remembered her anger, and it is implied that Frisk was rejected by her human family, though later evidence contradicts this, implying something deeper. She decided to read Toriel's second note and found that it may be Toriel's last words, detailing her hidden cache of secrets in her room. Frisk grew fearful, especially upon seeing the mysterious figure outside once again. When she got to Toriel's room, she found it was a mess, someone having already been here and taken the secrets. Beginning to panic, Frisk was able to contact Asgore. He rushed over, and upon learning what Frisk knew, he took Frisk to stay at Sans and Papyrus' house.

Papyrus was with Mettaton, leaving Sans as the only company Frisk had. He gave her some warm tea, and she appreciated his lack of prying questions. Eventually, however, she used his phone to call Terrence, who was with Greg, and had them come over. She went to Terrence for comfort when they arrived, and explained everything that she knew to them. She had Terrence cancel the party. After some time, Asgore and Undyne showed up, beaten and exhausted, claiming that one individual had done this to them. It was here that Asgore revealed he'd been given a call, and alerted to the death of Toriel.