How do I write this Contradictory Character?

I have a character in a work (btw this is the same work I was talking about in the 'avoiding a Cliche storm thread) who in order to pull off what I have in mind for him, it would take pulling off a perfect contradiction of charisma , likability and dis-likability

He's a teaching assistant (working with his father, a headmaster) in an unusual magic school that is training it's students to be ...well essentially sorta royal secret agents, /"Royal scouts". Major projects are 'field assignments" to put their powers to the test. This is a part of the society. They're usually put in groups to protect one another and the most dangerous assignments are given to the oldest students. But it's still something of a "school of peril"

However he and his father have other loyalties against the King and Queen of their society and they are trying to 'use' the students in a roundabout plot to incite an international incident and knock the King and Queen out of power. He's pretty much planning to use the kids to work against the one their supposed to be working for without them knowing. (he plans to have the corrupt bureaucratic of nobles take the king and queen's place).

But at the same time he's subtle and he's a good teacher. He's a natural leader. I don't want the twist to come out of nowhere but at the same time I don't want him to be 'Obviously evil". But more subtly manipulative evil that is very damn good at what it does. He needs to be a good teacher and effective teacher (not the bullying type like Snape was) but still a crooked manipulator? Thoughts?

The easiest way to do it is to simply keep in mind who he's dealing with at any point in time. He's not self-contradictory, he's hiding an agenda from a group of people. Which virtually everyone alive does, to some extent (some more than others, of course, but everyone does it a little). He's partitioning off chunks of his life according to whether the person he's with Needs To Know. For instance, I may talk to a couple friends about my love life, but I don't talk to my co-workers about it — they don't Need To Know that information.

He seriously want the kids to be good at what they need to do, so there's no contradiction between him caring about them and being the best teacher he can be; presenting one aspect of himself to the students when he's dealing with them.

But when he's dealing with the other conspirators, there are things that he'd talk about or do that he'd never mention around the students.

Reminds me a little of Alonzo Quinn from Person Of Interest. Or Loki from THOR, who at first seemed really nice and genuinely kind.

One thing that will really inform his characterization, I think, is how he views his pupils. Does he actually care for them, and want them to learn? Or is the 'good teacher' thing more an act than a reality, and does he see them as little more than a means to an end? I think the first is more interesting, personally. He could easily see his manipulations as being for their own good, and justify his use of them as creating a 'better world' for them to live in once the plan succeeds.

It doesn't have to be either extreme, of course. He could be genuinely fond of his students, perhaps, but still see them more as tools than people.

Yeah this describes him pretty well.