TrueDarkSword
A young teen dies, and by a stroke of cosmic luck, he is merged with another world's version of himself, waking in a shallow grave. Stripped of most of his memories by the experience, the teenager has to adapt to this strange, oddly familiar world that's filled with monsters of all kinds.
It helps that he's not exactly alone, nor helpless. Broken memories guide him as a hollow whisper, a chaotic power thrumming in his very soul. Now, if only he could figure out how to talk to people...
A SI into a RWBY OC, into an AU Remnant, armed with one of my favorite powers of all time. Weak to Strong. SI has Cole McGarth's powers, albeit nerfed at first.