I'm scratching my head.
First off, there's not enough information to diagnose your problem, but it is not possible that it is a matter of profile. If only a handful of profiles out there do it for you, "sterile" isn't the right word to be using. I'm not questioning your preferences, but a direct profile sounds exactly like the line out of the amp it profiles., so much so that people regularly fail blind A/B tests. There's probably a million Youtube videos like that.
You then proceed to say you want your guitar to be "dark", and that what you get is a guitar that sounds almost "happy". I read the word "scratchy". Overall I'm not getting a very good idea of what your guitar actually sounds like to begin with, and I'm not really grasping how you would like it to sound. When you say that it sounds "scratchy" and you want it to sound "dark", I'm assuming your guitar is pronounced in the mids, and you want a typical, mid-scooped BBE Sonic Maximizer sound, but without the high end. That is easily EQable, but there are parameters in the amp section that interact with the EQ. Clarity and definition both do something that sounds like EQ. If they are set too high, they will make the profile sound artificial (unnatural). There's also the "Character" parameter in the cabinet section. That too can cause some artifact-like things in your signal if set too high. And then there's the Pure Cab parameter which smoothes out peaks in the frequency spectrum. They all play a role in your tone, and the way you're describing it, it sounds like you should look at those settings and play with those.
What kind of guitar are you playing? And what kind of playback system do you use? FRFR speaker or cab? Monitors? Headphones? I'm just asking to ensure you've ruled out that it's the speaker you're using that is making it sound "sterile". And about the guitar because the "whine" noise you're describing makes no sense, so I'm wondering if you have a hollowbody or an LP and it could be your strings ringing out above the saddle or below the bridge. Either way, that's not something I've never heard anyone say about the Kemper before. Mine definitely has no whining noise on any profile, and I've probably demoed a few hundred profiles. They only ever sounded sterile or unnatural to me when those parameters I mentioned above were set to some out-of-whack value. Imagine if your playback system is bright and the person that made the profile you are demoing used a playback system that had a darker signature. Any settings in the profile would be dialed for that speaker that was darker than yours. Everything would sound brighter on your system. That could be a thing maybe?
I also know some people have reported that they updated their unit, and afterwards it sounded like shit (thin tone, I believe the word "shrill" was used to describe it and I connect that to your "scratchy"), but a factory reset made it sound like normal again. This is more of a long shot than anything else I'm posting, but thought it was worth mentioning. I've heard three or four accounts of people having that happen to them in the FB group.
Like others already pointed out, if you post a clip of what it sounds like on your end, it's way easier to understand what's up and give you the right advice. Also, suggesting a song with a guitar track that has a tone you like would benefit you as well.
Edit: okay, I just kept coming up with more stuff to add, this is my fourth edit lol. Anyway, check this out:
This video shows you what the Definition parameter does to the signal. At 10, everything sounds a lot more scratchy to me than at, say, 2.
Seriously, are you after darker sound when you practice on your own. in a band or recording context? In recording it might work or not. It all depends on the rest. It can easily turn into just a muddy sound. With some mic's you get a darker sound and how you position the mic(s)on the grill makes a difference too. A bigger guitar sound? I suspect you're after beefier sounds you hear on records. They're either double or quad tracked. And quad tracked doesn't necessarily means it sounds bigger and fatter than double tracked. That's a myth. Period. Have you ever listened to commercial stems? It's the bass guitar that makes the guitar(s) to sound beefier.
ever since then, I've struggled with my sound. Maybe I'm just going crazy and complaining now, idk. But thanks for all the suggestions guys ?