Some people make the argument that Aurelion Sol was punished by Targon because they destroyed his stars and a black hole is a collapsed star, however, in his recall he makes a Wormhole/Black hole and travels in it. A worm hole is (theoretically, keep in mind I don't think this is possible to test currently,) two black holes that are entangled together then taken apart. A black hole is a collapsed star (as said before).
There for, Dark Star Aurelion would make sense. Maybe, its the side of him that does/did Targon's bidding, and because they destroyed his stars, that side of him went corrupt.
*Side Note: From my perspective, it seems like with a champion like Aurelion, his design and concept doesn't give Riot much to work with.