Twin Mind Immortal

Rowan died as he lived. Fighting.  For his bravery in battle, he is offered a reward. Reincarnation. Not just that, but he gets to choose where. He could be a cozy farmer on a verdant, magical world. Or a genius engineer on an advanced planet that hasn't known war in centuries.  His response is concise and simple, the same as he is.  "I wanna fight." Those three words, and a little too much excitement about getting to fight robot demons, lead to an accident.  The body he is reincarnated into isn't quite as empty as he was promised.  Vorn, the aspiring mage that formerly owned the body, isn't exactly thrilled about the situation either. They don't have much of a choice, though. Their options are to fight, or cooperate. Rowan would much rather fight monsters than a mental battle, plus Vorn's prospects weren't exactly looking that great even before this whole situation.  What's the worst that could happen by joining forces? Join Rowan and Vorn on their journey to become the world's first Twin Mind Immortal  Do not expect an overly serious story, there may be elements of that, especially in the first arc, but I'm making this purely for fun.  Expect: -Number go up -Magic -Mayhem -Ungodly amounts of dead monsters, elementals, demons, robots, and robot demons. -Cozy evenings reading inside -No Harem, and no romance at all for that matter (Except maybe tangentially through side characters, and plenty of bromance.)   -More bromance than I ever could have expected, seriously, if these two weren't aro/ace I would be concerned