Prayers to Broken Stone
Twisted by the effects of dragon sickness, Thorin banishes not only Bilbo but the entire company from Erebor. Days pass with no word from their missing leader and, fearing the effects the gold may have on the other dwarves, Bilbo decides to enter the mountain alone in search of Thorin.
What he finds may not be Thorin for much longer.
Or: In which the dragon sickness is slowly transforming Thorin into a dragon, and Bilbo must save him before it is too late.