Malice is an important concept within the world of the Shadow Hearts series. Whenever a monster is killed, its soul becomes vengeful and turns to Malice.
In Shadow Hearts
In Shadow Hearts, Malice is released every time a monster is killed by Yuri. It is stored within the talisman that he wears. As more Malice is accrued, the talisman changes colour from blue to green to yellow to orange and eventually to red when at maximum.
If Yuri lets the Malice build up to a maximum, he will face Fox Face in battle. Once Fox Face is defeated, Yuri will instead battle one of the Four Masks. After defeating them, Yuri no longer has to worry about accruing Malice.
In Shadow Hearts: Covenant
Malice plays a smaller role in Shadow Hearts: Covenant, as Yuri no longer accrues Malice due to the curse of the Holy Mistletoe. However, because of this, Malice flows from within him and attracts Monsters.
In Shadow Hearts: From the New World
Malice reappears in Shadow Hearts: From the New World as a key plot point. Rather than any character accruing Malice, Malice is being released from another dimension, which the party are working to stop.