villain's motives are dodgy at best.
I was watching a documentary about an aircraft designer who worked for the Nazis and it gave me an idea for antagonist design. I generally like creative types and aircraft designers are on my short list of good guys.
Like Jake Blues, I hate Illinois Nazis as well as the German ones. Did I say I generally like creative types? Well, I love German engineering. So, I'm torn.
Let's pause momentarily to reflect the nature of good and evil. Good consists of adhering to a set of perpetually binding obligations, but it's not an unfair simplification to say it's following rules. Evil includes breaking rules. One might think that greater evil is seen by more rule-breaking, and that's in part true. Someone who obeys all traffic laws, is a better citizen than another who only breaks the speed-limit. And he's better than another who also runs red lights.
To really get villainy out of a villain, the character must have several lawful, even admirable qualities.
Let's suppose you have a Nazi aircraft designer who's building a secret weapon for Hitler. In order to be an aircraft designer, he had to do his homework in school. And the kinds of students who cheat on their exams go into Politics, not Aeronautical Engineering. And this fellow has to have a decent work ethic, because you cannot build a secret weapon for Hitler if you're passed out from last night's drunken debauchery at the roulette wheel.
What I'm saying is that you will invariably have a great deal of good in an effective villain. In fact, you'll probably find that the person will be 99.44% good, with just one little problem that spoils everything. Like burnt soup. Most of the soup is not burnt, but the tiny bit that is burnt changes everything.
Michael Corleone who is a good boy and whose father does not want him to become a mafiosi. Yet, he is drawn into crime to avenge the murders of his family members. Evil in this world is like a train wreck with twisted metal all over that causes secondary and tertiary damage. Your villain should be like this train wreck who's chugging down the straight and narrow all happy and healthy. THEN something should happen to make the wheels come off the rails.
Because your villain started out as a good boy, he's had a chance to gain skills and reputation and accomplishments that will draw others to him. And he more good he is and does before the derailment, the bigger the potential damage afterwards.
In Louis L'Amour's novel The Daybreakers the Sackett brothers first make friends with Tom Sunday who is slowly turned into an enemy through bitterness and anger. And this makes him the perfect catspaw for novel's villain.
Your novel needs a villain as well as some minions. I suggest that you draw from the noblest people among the ranks of National Honor Society members, the PTA, and overall goodie-two-shoes. And having given them education, connections, wealth and influence, THEN devise something that'll derail them. Perhaps a sister dies of cancer in tragic circumstances and the brother blames God and lashes out after the manner of Captain Ahab. Or maybe his mother spins a lie that the hero gunned down his no-account brother in cold blood.
The easy part of evil is that it is predicated upon lies, and your villain can just as easily be knocked off the rails by lies.