and to he who is faithful I will grant eternity
Originally inspired by a line from this beautiful Moriarty character study fic by cj_ludd18 (who writes lovely Moriarty/Moran ;D), but this drawing is purely self-indulgent.
My mental canon for this is Moriarty making a deal and offering his soul/heart to the Lovecraftian ‘Old Ones’ mentioned in A Study in Emerald. So in exchange for his heart and a lifetime of servitude dedicated to evil and destruction, they grant him their favor (immortality, or something close to it)