Soulmates are not always romantic and we could have multiple SM’s, and then there are karmic soulmates. I could ramble on forever on this subject lol. BUT I’m not sure how the nice/mean combo would work. Sometimes people are in our lives to teach us a lesson. So you could def take something away from that experience

Depending on the extent of not niceness & meanness. But I'd be inclined to think; no.

Equal and opposite... Seems plausible

Opposites attract..

I don’t believe in soulmates