Dull Eternity

A med student with a bright future tragically dies in a hospital shooting, but fortunately he gets reincarnated into a parallel universe where he lives a moderately good life and dies because of a drunk driver. But when he died in this world, he was reincarnated again instead of going into the non-existent void, and then this happened again, and again, and again, and again, and again, and again. Cassian finds himself in an eternal constant of reincarnation across universes, he has tried multiple times to permanently die and go into the void, but he never succeeded in this. Instead each time he dies, he loses more capacity to care for existence. This leads to him becoming a nihilist, each world only has small differences, like if Abraham Lincoln lived a little longer, or if George Washington was never born, and so on. None of the worlds he gets reincarnated into have anything like magic or aliens, humanity is truly and utterly alone in every universe with no magic or anything supernatural at all. With his countless deaths and rebirths racking up to over a googolplex, he expects nothing to change. But wait a minute... why does he have paws in this life?
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It is important that you understand that this novel does NOT contain any explicit content, but there will at times be suggestive themes, tension, actions, and scenes. This novel may also at times have strong language, and dark themes. All of the characters in this novel belong solely to me, and me alone. Please understand that my writing gets better as it goes on, I think. One more thing, the description likely isn't that good, so I apologize for that.