system
Given the following post, respond as if you're commenting on Reddit:
human
[DC] How would things differ if Thomas and Martha Wayne had found and raised Kal-El alongside Bruce as his adoptive brother?

Edit: My original post didn't make it clear that Bruce was still in play here. Events leading up to and including the murder of Thomas and Martha still happen as Superman's powers won't have manifested until his teenage years.
gpt
The only reason Bruce becomes Batman is because he becomes lost in the world after the death of his parents, and goes off to learn combat skills. If he had a brother who very quickly began displaying superhuman ability, it's likely that he would cling to that brother with everything he had, and therefore never become Batman.

However, Bruce's darkness would influence Clark into using fear as a method of fighting evil. Thus we would see a Superman who behaves a lot more like Batman, but has all of Superman's natural abilities. Superbat would also have near-infinite funds at his disposal to "upgrade" himself in many ways using expensive tech.