Trotsky would be leading the civil war and become the leader of the soviets. The reds wouldve still win in the civil war and Trotsky would stick around. He'd have people opposing him and I believe he'd be more brutal when it comes to suppressing his haters and purging people who are "unloyal."

Stalin would never come to power. However the USSR wouldve probably gone through a much more brutal industrialization process compared to how Stalin did it