What if Rimuru was instead reborn as a primordial demon; the strongest in combat and intelligence. He reincarnated just before Star king dragon Veldanava created the omniverse; it was nothing but a void, his soul being exposed just a little to turn null made his soul undergo a change. Making him an individual with a high evolutionary potential

What if Rimuru turns Shizu into a slime? To save Shizue from dying from old age, Rimuru gives her his slime cells and transforms her into a slime, no half humans and half-slime or a half-breed slime/human or slimenoid. Join Rimuru and Shizu as the only slime species that can do skills, magic and are intelligent they are. Shizu will still look as her humans self but Shizu will have all the abilities that a slime can do and maybe even Rimuru skills too.