In her youth, Hanna dabbled in various studies, including business, science, art, and odd jobs. In their early 20s, both she and her sister Alonz occasionally joined their other sister, Pav, in adventures, to which Hanna seemed better suited than Alonz. But while they both enjoyed their adventures, neither of them wanted to make that a permanent lifestyle like Pav did. But it wasn't until 903, at the age of 43, that Hanna finally found her true calling. She became one of the founding members of the Marine Corps, which was raised among merfolk (mostly those of West Ocean, where Hanna happened to be visiting relatives at the time) to aid the Protestant Movement in its war against The Order. (Her decision to fight on the side of the Protestants caused a temporary rift between her and her brother Manat.) After a brief stint with the West Ocean regiment, she became the Brigadier of the First Sea regiment.
When the surname law was passed in 904, Manat chose the name 'Ericson' for his clan, named after Eric, whose idea it had been a century earlier to create merfolk. And so, this would be Hanna's surname for the next four years.
Also in 904, the newly established Second Order integrated the Marine Corps into its military. Manat, who had been in favor of the Order even before the war, helped facilitate this transition, using both contacts he had long had in the human world, and members of his own family. This of course included Hanna, though she was understandably reluctant to become friendly with her former enemies. However, the change ultimately led to reconciliation between her and Manat. Also, in the course of the integration, she met an officer in the Navy named Scott Botanical. As they got to know each other better, they gradually became friends, and eventually fell in love. In fact, they are the only known human-merfolk couple to ever marry (which they did in 908). At that time, Hanna chose to take the surname of her husband's clan, Botanical.
In 912, the Marine Corps chose not to involve themselves in the Chaos War, as many of its members were deeply conflicted about which side to choose. In 913, after West Ocean voted to become sovereign (in the Secession Referendum), the Marine corps' two regiments became separate organizations. At that time, Commandant Gilbert Tridentwielder assumed direct control of the First Sea regiment, rendering Hanna's position superfluous. She therefore retired from the Corps, to pursue other interests.