The power of its namesake can be unlocked by the Finger Reader. Alternatively, it can be used to gain a great bounty of runes.
The Fire Giant is a survivor of the War against the Giants. Upon realizing the flames of their forge would never die, Queen Marika marked him with a curse. "O trifling giant, mayest thou tend thy flame for eternity."
While Remembrances can be duplicated more than once through different Wandering Mausoleums, they can't be traded for a copy of an already obtained item in the same playthrough.