How we cite our quotes: I cite by line number only.
Quote #1
O what can ail thee, knight at arms,
Alone and palely loitering (lines 1-2)
The knight seems almost ghost-like in these first lines. The speaker finds him all "alone" and "loitering" near a lake. He's pale like a ghost, and the "loitering" seems like a ghost that haunts the place where he died.
Quote #2
I see a lily on thy brow
With anguish moist and fever dew (lines 9-10)
The speaker can tell that the knight has a fever. High fevers can cause hallucinations or visions. Is it possible that the knight is just a sick man who had a feverish dream about a fairy lady who seduced him and then ditched him?