I picture Clark as a person who is very passionate about social justice. He's incredibly intelligent - a perk of coming from an advanced society where the dumbest person on the planet is intelligent enough to be a celebrated theoretical physicist on Earth - but he's also a man of action. He might
look like someone who rushes into situations without thinking but the truth is that it only takes a second (maybe two) for him to come up with solutions to fix whatever problem he's trying to solve. That doesn't always make him the best or most reliable team player, which causes friction with both the Justice League and (to a lesser extent) his Planet colleagues at times, but I imagine he'll become easier to work with as he ages. I imagine him in his younger years as a slightly cockier version of the MCU's Steve Rogers. As an older man, I picture him as wise and zen - but never without that slight cockiness, that absolute belief in his own power and the righteousness with which he wields it; he's mellowed out and all, but you never quite forget that he's not one to be ****ed with.
As Superman, he doesn't often speak. When he does, it's because he has something important to say. He's kind and reassuring, but he prefers to expresses himself through his actions and demeanor than through words. As he ages and becomes a bit more like the Superman we all tend to picture in our heads, he becomes a skilled orator.
As Clark: he's mild-mannered but passionate and it mostly shows in his writing. Clark is just as much of his true self as Superman is, but Clark can express opinions and relax in a way that Superman cannot. He can express explicit dislike for people who aren't corrupt businessmen, he can grab a slice of pizza without being mobbed, he can ask a woman out on a date...you get the idea. The "nice guy" at the office who not a lot of people really
know, but everyone likes him. He goes out of his way at times to comedically emphasize his physical resemblance to Superman - the best way to hide is in plain sight, after all.
Power level: I picture him starting at the Golden Age/Fleischer/
S:TAS power level and peaking at...well, somewhere higher.
He's the strongest man on Earth but he can't move planets, survive in space for more than a few hours without assistance, or actually survive going through the sun.
My reason for wanting to temper his power a bit is so that combat and super feats can be done as practically as possible - I've had enough of ****ty, video game-y special effects. They're unavoidable, but the less of them, the better.
