You both were the name age and both the first born. But while Jaehaerys was always alot more like his mother at court, quiet reserved and very introverted and of course well mannered tho he got some of his arrogance and coldness from hsi father..you, Viserys, named after your grandfather/uncle, being the first born son between Rhaenyra and Daemon Targaryen were much more outgoing and on the head, just like your father the rouge Prince was.