Well I would argue the mc has some motivation considering he’s been made a slave. Sure a well kept slave but a slave nonetheless. So has Tahir.
That's kind of a situation where modern values might conflict a bit with past reality and assumptions though.
They basically went from living a life of absolute squalor where they have to commit petty crimes just to survive and could die at any moment, to living in luxury that's almost unknown to the average person. The modern perspective (especially in the West) tends to be that "freedom is more important than anything", but for most of human history, plenty of people would see trading up to pampered slavery to absolutely be a positive. A well-treated slave may still be a slave... but they're also
well-treated. Going from wearing dirty rags and not knowing where your next meal is coming from or whether you're going to get stabbed just for being in the wrong part of town at the wrong time to living in a palace, eating sumptuous meals, bathing regularly, and wearing wonderful silken vests while getting to sneak into the harem for sexy times is pretty much heaven.
Especially since - arguably - the Sultan
already has the power of absolute life and death over every one of their subjects anyway. You're pretty much his slave regardless of whether or not you're acting as a servant in the castle or toiling away in the streets. He's just more likely to ignore or overlook you when you're a homeless nobody, but he could still have you killed or tortured on a whim and no one's really going to object or stop him.
For people who grew up in that sort of world and have come to implicitly accept the idea that things will always be that way and the ruler will always have the power to do whatever they want, the idea of freedom is kind of nebulous. It's not something everyone's going to aspire to all the time, even at the expense of their comfort or their lives.
And doubly so if they're being asked to help kill a ruler who has a reputation for being relatively just, and who has never done anything all that wicked to them personally, in favor of the unknown outcome that would follow where someone even worse could wind up in power, and your own personal circumstances could (and likely will) radically change for the worst. Even if you
don't get caught (because getting caught pretty much guarantees horrific torture and death). Can't even use glory or fame as a motivation, because you're just as likely to be reviled as a traitor and a monster as you are a hero or a liberator (just ask Brutus).
I'm not saying there's no possible chance that the main character would ever find value in some form of freedom, or even just an escape from his specific situation (especially if that's how the player wants to perceive him), but there's plenty of motivation to
not play him that way.
