To understand why your character is driven toward a certain goal, get to know their positive and negative traits, as well as any significant emotional wounds that might be motivating them. Then you can explore the various kinds of conflict that could block them as they move toward their goal.
With hindsight being 20-20, there can be a temptation to "fix" something that didn't work out as expected. But when a character becomes judge, jury, and executioner, it can lead to terrible fallout, especially since their emotional investment in the situation probably means they're biased. If the character barrels ahead despite evidence that their judgment is flawed, or they realize others will suffer as a result of their actions but they don't care, their motivation is a dark one.
FORMS THIS MIGHT TAKE:
Going back in time to erase someone from history (regardless of the consequences) Killing someone (a political leader, a military adversary, a narcissistic patriarch, etc.) because they are a disruption to the status quo Taking what the character is owed (a life for a life, someone's livelihood in exchange for a lost fortune, etc.) to balance the scales when justice failed Destroying technology or medical advancement because its original use has become corrupted Destroying something good because it also does harm (lumping the good in with the bad) Destroying a protégé because they are using their skills in a way the character doesn't like Revoking access (to water, land, or the ability to reside in a particular country) when politics get complicated or resources are depleted The character casting out (or killing) their own child for being a disappointment or because they regret having them in the first place Taking an animal to a kill shelter because it's a headache to care for
HUMAN NEED DRIVING THE GOAL (INNER MOTIVATION):
There are five basic human needs that, when missing from a character's life, could motivate them to pursue this goal. The following needs are all possibilities, but only one of them should be the primary driver for any given character. For more information on the relationship between human needs and outer motivations, please see this Character Motivation tutorial.
Esteem and Recognition: A character who feels they are powerless may seek to reclaim their power by risking everything to bring down a person or company who they feel has done great harm.
Love and Belonging: A character without love and belonging can act against others with clinical detachment, bringing about a horrific result without being bogged down by moral questions of right and wrong.
Safety and Security: When threatened, a character will lash out and use their skills to neutralize that threat, whether it is real or imagined.
Physiological Needs: If survival is threatened, a character can detach themselves from moral obligation and make choices because they have adopted an "it's me or them" mentality
HOW THE CHARACTER MAY PREPARE FOR THIS GOAL:
POSSIBLE SACRIFICES OR COSTS ASSOCIATED WITH THIS GOAL:
ROADBLOCKS WHICH COULD PREVENT THIS GOAL FROM BEING ACHIEVED:
TALENTS & SKILLS THAT WILL HELP THE CHARACTER ACHIEVE THIS GOAL: