Firstly, what I will suggest is starting from a point that's familiar to you, and drawing it out to its extremes. Or picking a particular type of darkness and asking yourself what it's the least it would take to get a character to that point, from where they've started.
But aside from that, I do find it worth pointing out that evil comes from more places than just 'the darkside' and 'the Sith'. You may or may not find these avenues easier to get into than the typically more overt evil of the Sith.
Allow you to regale you with my experience, lol.
I wrote Sith for years from the late 90s up until... I wanna say 2017 at the latest. For me that was very much drawing from what I knew at the time. Writing Sith and that darkness came easy, but at some point that resolved for me and it became harder to write. Not because I no longer enjoy the concept of that kind of evil as a genre (I was to somewhat raised on the horror genre and still enjoy it), but it's a heck of a lot more difficult to access now, as creative output. And I think I may have gotten bored with writing it, to some extent.
The kinds of evil I
do find easier to access these days are found more in the shades of grey. The less obvious/atypical avenues that don't make use of the darkside or aren't explicitly Sith. Ones that are largely driven by a shared belief between the characters involved.
Belief can be a very strong driver for a character. It drives how characters act and react in many scenarios.
Why they believe what they do also matters a great deal, here... maybe something (or several somethings) happened to put them on that path because they weren't resilient enough to weather the trauma (it's worth noting that you don't always need someone to take advantage of your character's weakness or low point. and pull them into the dark; it
can happen as a natural outcome of unresolved trauma), maybe they were simply indoctrinated, or they were born into it and raised in it; those are the three most common ways that 'darker' beliefs can happen, here. Some can be simultaneously true for some characters.
But anyway...
Evil driven by beliefs is what I like and have liked about writing:
*
Imperial Knights, and Imperialism in general: here the belief can be characterised by the view that both major proponents of the far ends of the Force spectrum (that is, the Jedi and the Sith) are extremists, and in general have failed at bringing a definitive end to the eternal conflict, and therefore, have failed peace. The answer here is effectively peace through ORDER, and that delineates in some rather horrific ways with the lengths its proponents will go to preserve and propagate the Imperial State, but the evil here can also be banal. Many imperial citizens may believe they are serving a good... that's what effective propaganda can do (you've seen Andor, right?). The Force in this case is often seen as a tool, and sometimes, the Force is even seen as property of the State.
* with the
Ashlan Crusade for the years that I did: Religious Lightsiders, who saw the lightside as the Goddess Ashla. A faction for whom a core tenet of the founding of the Crusade was the eradication of the Sith, their culture, writings, art, etc. That's genocide in all its forms. There's still Ashlans about, but they are definitely a minority group these days.
* with groups such as the
Lightsworn, militaristic lightsiders who have tread along the same lines to the Ashlans, though without the religious component. This one and to some extent the Ashlans tapped into the idea of Jedi Lords/Army of Light.
I also have to say that the 'bright spots' (the downtime, the slice of life, the sweet stuff, the socials) can and do still happen in these scenarios. I've enjoyed them myself.
I hope this helps.
