"Thirsting for revenge, Jack Frost donned his Ice Vest to become the dark hero known as... Frost Ace. What will his sorrow frozen heart choose? Will it be Vengeance? Mercy? The gears of Fate continue to toy with him..."
—Strange Journey Compendium
He first appears as a lowly Jack Frost in Sector Carina's basement mourning his family. He begs the protagonist to get him an Ice Vest so he can become powerful and get revenge; upon obtaining it, he transforms into Frost Ace and grants his benefactor the Frost Ace Special Fusion and the Frost Cannon before leaving to seek vengeance.
His Special Fusion consists of Jack Frost, Tam Lin and Power.
Shin Megami Tensei IV
"Jack Frost after he donned his Ice Vest and transformed into a superhero. Little is known about him, but rumors says he was involved in a tragic incident and now burns with vengence, though his heart is still frozen in sorrow. As Fate toys with the dark hero, what path will be choose? Mercy? Or vengence? Still unable to come up with an answer, he continues his long battle, hiding that cool, cute face of his behind the mask."