When the Astryd family thought of places to have privacy, their residence and Garden's underground base were the only things that came to mind, but that wasn't entirely true. There was one last place, one usually visited only by Kyuru or Desmond, and that place was Athena's tree house and the meadow around it.
Despite her childish and clueless attitude, Athena was, after all, a born predator. The cute harpy would have no problem taking the life out of any intruder; as such, her territory was relatively safe. Also, the hypnotic flower garden around Athena's treehouse functioned as a natural barrier against humans or other sentient beings, so privacy was not an issue.