I'm going to go for an Eldritch researcher build, so my source of mutation is Gifted. I was already an impoverished person in the Underhive, so I sought forbidden knowledge in the belief that I could improve my circumstances, mutations be damned. What I discovered...could change everything.
Free Mutation: Ascended Mind. The key to understanding begins with yourself and how you perceive the world. That was the first lesson I learned.
Extra Mutations: Seer's Gaze, Regeneration. The second lesson I learned was that there's a pattern under the shifting currents of the present. Even if it's just for a few moments, if you can recognize the pattern and its connection to the Now, the Future path becomes clear. The third lesson was that Life will always try to restore itself, even if it has trouble remembering the little details. Remember how you were, remember how you're supposed to be, and your body will follow suit.>>64972295
Ichor Blood: a side-effect of my Regenerative power. While the Life in my veins desires to repair and heal and restore, when outside my body it seeks to destroy everything that's not itself.
Night Terrors: gaze into the abyss, and it will gaze back. There's a cost to being able to see the pattern of the future - I sometimes catch a glimpse of... something, almost alive, lurking in the swirls of events and choices. Only my unconscious mind can properly put together the pieces, and the answers it gives me are far from reassuring.
Controlled Progression: the culmination of my research. Regardless of their source, mutations do not have to be random. Through the clarity of an understanding mind, through the strength of an indomitable will, the development of my mutations is entirely under control. However, there are still rules I must follow. Nothing is ever free.
Extra traits: Survivalist, Heightened Senses. Long treks into abandoned ruins, searching for clues, have acclimatized me to self-sufficiency.