Twin mecha musume,

They were twins, but calling them two people never quite felt right. White-haired and black-haired, they had grown up finishing each other’s sentences, anticipating each other’s movements, and knowing what the other wanted before a word was spoken. Then came the exoskeletons. One wore white. The other wore black. At first, their engineers thought the matching armor would make them easier to coordinate. They quickly discovered that coordination wasn't the right word. The twins didn't coordinate. They simply acted. When one stepped forward, the other was already moving. When one raised her massive mechanical glove, the other shifted into position. When one turned, the other turned with her. On the battlefield, their movements became almost impossible to distinguish as separate decisions. Two bodies. One rhythm. One instinct. One will. Their enemies eventually learned the most important lesson: There was no point trying to distract one twin. If you confused one of them, you had confused neither. Because somewhere beside her, her other half already knew exactly what she was going to do.