Help finding 2 transmigration stories

In the first story the MC transmigrates into a book where the original host picks up and bullies a puppy that turns out to be the ML. Later ML gets into an accident and wakes up back in his body. Also original host was switched at birth and his bio parents are rich and find him. His not dad was abusive and MC eventually tells bio family about it and says he’s original’s split personality. Eventually not dad tries to kill himself and Mc and switched at birth son help him. MC spends a lot of time believing he’s only here temporarily and original host will come back which pisses ML off when he realizes. There also maybe a crystal or something that might have caused the transmigration and an antagonist wanting that stone, maybe?

I actually barely remember story 2, just that MC transmigrates and finds out his older brother also transmigrated and they reunite at like a bar maybe. It was pretty cool that his sibling was also in that world.

Please help! 🙇🏽‍♀️