Provided you own the intellectual property of a character, you can 'transplant' them from another setting. Importantly, this involves stripping from them all traces of prior copyrighted material - for example, changing the names of places where they grew up or people they may have known - in a process we call sterilization.
When a character is sufficiently sterilized, they can be submitted for evaluation in the character submission sub-forum where moderators and players will provide you with support in improving your character to bring out the best in your work, make your character something you can get the most out of and make them ideal for the setting.