I have been working on this one for weeks as I had a hard time with a solid design for her but I like how I did with a Broken and Determined Raven
This one had to make the choice to stop the human from killing her friends again so the only way she saw this was possible was to do it herself, but at the cost of her trust(Alphys, Muffet, Undyne) and love for them(MTT, Torial, Grillby) she back-stabbed them(Sans, Asgore) and killed them without remorse (Flowey, Guard Dogs). The only thing she can get from them was their powers.
What made her broken was when she had to make the last kill in her world: Papyrus
The last one she hurt was Papyrus who tried to talk her out of it but when she delivered the killing blow he broke through but it was too late to heal him or save him from dying so she keeps the scarf as a token that he always seemed to see good in her even if she couldn't see it.
What makes her Determined
It is from all the kills all the LOVE she gained made her so strong and where she felt most of their abilities activate when she met the human in her state, where they hit her she never lost any HP, her main abilities are from Flowey, Sans, and Undyne as they were the strongest and easy to use for her along with her own attacks. Even when she should die her SOUL wouldn't brake the fact was it couldn't as her SOUL was broken from her actions but kept together by her sheer determination.

Raven belongs to me
Undertale belongs to Toby Fox