Shadow Slave by Guiltythree

-MC becomes a slave
Honestly, don't know how to explain this one, it's literally in the title of the novel. At least, I never thought he wouldn't become a slave at some point before reading. His Aspect (Class) is Shadow Slave and the Spell/System itself says it would be beneath him to be a slave with no master so he has to look for one. Of course, he tries not to become one but Fate has things instore for him and he is practically forced to become a certain characters slave. This literally changes nothing in the story so far since that character hasn't been seen since he became their slave. And honestly, even if he didn't become their slave, nothing would have changed. MC said in the chapters I've recently read that at least he had the chance to choose his Master while others are forced to serve people without even knowing. Even if he didn't become this persons Slave, he would have still chosen to follow them. And so far, we know nothing of the benefits for him becoming their slave yet so it's hard to tell if it's a definite bad thing yet. Of course, if he is ordered to do something, he has to do it but we don't know how his Master would go about their role yet. He has also stated that even though he doesn't really mind him becoming their slave, he isn't exactly happy with it either. This left him saying that he wants to grow strong enough to break the shackles that were forced upon him by both his master and fate itself (this doesn't, however mean he hates his master or wants to kill them. If anything, he wants to be able to stand with them as equals).

-MC starts off as "smart" and ruthless but changes soon after.
This one is pretty simple to explain. The MC grew up as a Street Rat in the Slums of the city. His "Smartness" comes from his ability to deceive others into doing his bidding. He's not actually smart, perks of never going to a school, but he eventually becomes more intellectual (especially since he loves to try and piece together the history through whatever information he can find). In this novel, when a person gets an Aspect, they also get a Flaw to go along with it. The MCs Flaw is that he can only tell the truth (afterall, what use is a slave if it has the ability to lie to others and it's master). This doesn't mean he can no longer deceive people, it just means he has to chose a different way to deceive. For instance, the MC has taken the approach of boasting about his achievements in a fashion that it seems like he is a compulsive liar when in actuality he is telling the truth. The Ruthless part never disappeared. He is still plenty ruthless to his enemies. Does that mean he wants to fight enemies 1-2 levels above him? No, he knows he isn't strong and he just wants as peaceful a life he can get so why would he want that.

-MC seems like a Simp
I can somewhat see it but honestly, if you think about it for more than a couple of seconds, you can see it's not true. This comes from the fact that, who I assume to be the FMC, is a very charismatic character and literally the first person the MC can trust in his life. He doesn't love her. In fact, he seems to be more attracted to some of the other side characters more than her. But not only is she a charismatic person and essentially the first person he could trust, she is also extremely strong for her level. I can't give a quantifiable level since it would be a bit of a spoiler but it's definitely up there.

-The Author makes questionable choices when writing
This mainly stems from one incident when there was a time jump and then 20 chapters after the time jump it goes back and explains everything that happened during the time jump and it takes 40 chapters to do so. It makes you question why he just didn't do a time jump but trust me when I say it makes for a much better story that it would have if it just stayed linear.