Memory! =) Are you sure Harry's insane? LOL The only difference is that they are now in St. Mungo's instead of Hogwarts - other than that, they are facing the exact same thing, and, wonder of wonders, together, while the rest of the world either 1) does not care, 2) does not trust them (or thinks Harry's crazy, in Harry's case), or 3) is afraid of them b/c they are either intimidating (Snape!) or spouting 'nonsense' (Harry!).
This St. Mungo's scene is an allegory for what their entire lives have been like. Thank you for writing this, eeyore9990! *loves you*