Ramble under the cut if you wanna hear about my thoughts on these two
Since the game didn’t give these two definitive personalities, I will. Had the idea that 56 is more outgoing and perky, she loves making new friends and just absolutely lighting up the room. Her brother 78 wants to give off that sorta cool, aloof demeanor, so he doesn’t talk as much, but 56 constantly drags him into social situations and tries to get him to be more genuine with other people. 58 also has a shorter fuse, so when she’s about ready to throw down 78 steps in and tries to mediate the situation. Also since they’re twins they have their fair share of messing with each other in that classic sibling sorta way, but it also means they’re perfectly in sync when it’s time to boot up their software and show everyone what being programmed to dance really means.
I do imagine that after helping Dr. Tan, their reputation is shaky at best, but it just gives them more motivation to turn things around and make a name for themselves separate from him. After you unlock them, the game tells you that their programming glitched out and they’re not evil anymore, so they prolly just wanna find a career in being their own duo. Idk what they do in the third game, or if they’re solely just playable characters, but idk how to find more info on them besides like, playing the game myself, which I don’t have.