Oh man, this is such a beautiful AND ABSOLUTELY PAINFUL piece @sagescider (and I mean that in the best way possible). The idea that Dess "wasn't really the greatest person" is one that really intrigues me. And I absolutely adore how you do justice to that concept in this art.
The first thing that stood out to me was that Kris had their hand out and it was bloodied. The way Dess is looking at them indicates that she's not looking at them because she wants to see their hurt hand and look after it... because she's the one who hurt it in the first place. It's a common (and cruel) form of corporal punishment to have a child disciplined by having their hand out and then it being whacked or smacked with some kind of cane, rod, switch, stick, or belt. You know why Dess is holding a stick while seizing Kris's hand like that? Because she used that hockey stick to whack their palm.
You can clearly see from the body language, from the way Dess towers over and intimidates Kris, that she is definitely livid with Kris for doing something, and this is further emphasized by Kris's avoidance of eye contact and the expression of guilt and fear on their face. My guess is that it was most certainly because of a prank Kris pulled, specifically the one where Kris would pretend to rip out their heart/soul and chase Noelle with it, since Kris is holding a (glowing) heart.
This is further emphasized by how Dess is actually crying herself, which implies what Kris hurt her feelings by pulling that prank on Noelle... but she dealt with it IN THE WORST WAY POSSIBLE BY RESORTING TO PHYSICAL HARM AND CORPORAL PUNISHMENT! It's like she's taking after the worst qualities of her mother, Carol: her overprotectiveness and her willingness to be harsh and hurtful toward the people close to her. And that's what I also love about this piece: how it emphasizes her flaws without going overboard and presenting her as evil or inherently cruel.
The issues in Dess's relationship with Kris and their character flaws on display here, you could also see as an omen of things to come with what that relationship would turn into when she became the Knight and Kris made that promise.
Additionally, you could interpret this as a metaphor for their relationship now, especially since the heart can be seen as the SOUL. The hurting Dess is locking Kris into an unhealthy relationship so they fulfill their promise to her with the SOUL, all while hurting them severely in the process, not just physically but emotionally as well.
Also, I absolutely love this design of Dess and how intimidating they look and how you capture her rebellious, unorthodox natures: the huge boots, the ripped shorts, the barely visible underclothes, the black hair, the stained fur, the ear piercings, the oversized leather jacket, her gloves, the little band around her arm, the spiked belt. I also love how her fur colour closely resembles Carol's! And coming back to the oversized black leather jacket, you could say it's the one from Asriel, and seeing how it's black and spiked also hints at her future as the knight, as the Knight is well, pitch black and also has shoulder spikes. Not to mention the 12 on her tank top is a nice touch, given that December is the 12th month and all that! Oh, and how her face is more deerlike, particularly with the mouth.
As I said before, beautifully painful! Very great job on this!