how would you imagine five hargreeves’s personality if he had grown up alongside his siblings ? What would he had done? Be depressed unfulfilled university proffessor? Work for CIA?
Honestly I think his personality would mostly be the same. In season 1, the flashback showing the day Five left, we see some of his personality at that age. He's brash in the way he got everyone's attention. He demands that Reginald teaches him time travel. Gets frustrated easily when he was told no and got an explanation a to why, and immediately tried to prove himself by showing his special jumps. He ran away to prove he could do it without thinking of the possible consequences showing that he lets his pride get the better of him. But we also see in the bank robbery flashback a more light and playful side to Five. He taunted the bank robber and joked to him about his "badass stapler". I could see him having fun with the whole bit. We also know how much he cares about his family, even if he doesn't say the words aloud. But I don't think he would have a great relationship with them even if he stayed. We see in a training flashback that he jumped in front of Diego to be in first. That probably wasn't the first or last time situations like that happened. Both Five using his powers to get the upper hand in training and vise versa. These things would probably fester over the years. I don't think he would hate his siblings, he would still care for them all. What we saw from every season (I don't believe in season 4) is how hard Five worked his whole life so they could live. Feelings that strong don't just develop immediately, they had to always be there even if they're pushed deep down. But he probably wouldn't be super close with them. It would probably be on a level similar to what we saw the rest of the siblings have in episode 1. He would care for them but would overall drift away as he got older and get snippy with them. So while I think he might still be prideful, brash, easily frustrated, demanding, sarcastic and the other qualities we see in the show. I think we'd see a more of a playful side to him as well. He might not have as short of a fuse, less of a bite in his insults, and might joke around with people sometimes. I don't think it would be a huge personality change, we would probably still recognize and be able to point out parts of his personality from the show but be able to see the differences from how he grew up.
As for what he would do? No clue. He most definitely would have left the academy when the rest of his siblings started to. I think it would be either side of the spectrum. He might either be successful, teaching in a college, or a scientist/mathematician, possibly some kind of law enforcement like Diego tried for. Or he would let his temper and pride get in the way and end up getting booted from the program. It would be one or the other. Success or just wandering through life unsatisfied. I can't see him being in the middle of that spectrum. But he would have grown up the same way his siblings did and we saw how all their lives turned out.
