Lansun,
as far as I know Yoshimo has to be with you in the asylum - there's some dialogue where he expresses regret and sets the scene for the heart 'quest'. If he's not with you then it doesn't happen.
Re Aerie - have you done the Unseeing Eye quest ? The Girdle of Fortitude sets CON to 18 for 8 hours - very handy for low HP characters
Kez