I need to talk about Serkan's personality and it's going to be a long rant so here is what I am going to do: I will talk about why he acts the way he acts based on my opinion on his back ground and then a clumsy analysis of him for each episode.
I think the main reason I understand and relate with him so much is that we are both INTJs (at least I think he is), so I get it when people say he is emotionless or a robot because I was told the same many times.
That said I have to state clearly he is far from a robot. He has feelings, maybe even deeper than anyone else. He just chooses not to show them.
Personality and emotional development rely mainly on how someone deals with psychological crises rising on the different phases of life. And we see that clearly in Serkan's attitude.
Before his brother's death, he could have been an introvert having difficulty showing his emotion as well, but we know he loved his brother. He possibly was his backbone, the person that listened and guided him, his friend and role model, then suddenly he lost that (we don't exactly know how). Not only he has lost a brother, but an opportunity of being supported and loved.
He was a child needing emotional support, he needed his parents with him telling him it would be alright, that they would get through this together, he needed someone teaching him how to grieve and how to cherish his brother's memory. And he found none of that, instead he was abandoned, sent away to deal with all of that by himself. That right there is a psychological crisis, for a child to be alone all of the sudden. I bet his young naive mind made him believe for sometime that it was his fault somehow, that he wasn't loved.
I'm sure his life in boarding school was not easy, he probably was teased for the absence of his parents, he may have fought and was in trouble many times before realising he doesn't have a chance to make a single mistake (as he's told his father). Making mistakes is for children who are protected and loved, who have guidance; it was a welfare he couldn't afford. The good thing though was that he became friends with Engin and learned to trust him (we don't know how but I am sure it took years).
Later he went to university without the help of his parents, became a top student as he wanted, he made every decision right, with no mistakes, he grew in his field without help. He was confident in his knowledge, and he was going to make his father proud. He became friends with Kaan and Seline, so far so good, right? Wrong his father was not as proud as he would be if it was his brother , Kaan turned out to be untrustworthy. Disappointment yet again proving that expectations could hurt and trusting was never a good option.
He learned his lessons the hard way throughout his life: You are on your own, make no mistakes, read people well, who wants to be trusted needs to earn it, make it through by yourself.
He was never taught that he can ask for help, that mistakes are opportunities for growth, that he can trust without reasons.
So here we have a logical smart man, whose every phase of life taught him that showing emotions is weakness, that vulnerability is dangerous. Do you expect he would be open and all fun? No, he developed his defence mechanism, a cold exterior, and built unbreakable walls around himself.
It's sad really how he walks by himself. His friends are Engin who listens without judging, Pırıl who is the most trusted when it comes to business, and Sirius the comforting silent friend. Yet he doesn't have that someone he can go to when he feels overwhelmed, who knows every single thing about him and is there all the time, that can make him feel better with a hug. He has friends he truly loves and yet no one that he dares to show his true self to. He bottles all his feelings, frees them only when he is alone. No on is to know the depth of his feelings.
Add all of that you get one Serkan Bolat, a genius architect, completely confident when it comes to his businesses, extremely insecure when it comes to his emotions. A loving son and friend, who would do anything for his loved ones without them knowing. A strong willed, always right, know it all devil. Not a robot, never a robot.