Alex would probably be both scared and defiant at first. He's a brave kid, so he'd likely try to find a way to escape right away. He might also try to talk his way out, using his intelligence to reason with Yassen.
At the start, Alex would be in survival mode. He'd be constantly looking for weaknesses in Yassen's setup to escape. As he spends more time in captivity, he might start to analyze Yassen's actions and words more closely. If Yassen offers him any information about his past or about MI6's secrets, Alex could be both intrigued and suspicious. His reaction would also depend on how Yassen treats him. If Yassen is harsh, Alex would be more resistant, but if Yassen is more manipulative and tries to befriend him, Alex would have a more complex reaction as he tries to figure out Yassen's true intentions.
The Quinx Squad could react with a mix of respect and wariness. They respect power, and Kaneki has a lot of it. However, they are also loyal to their cause of protecting humans from ghouls. Meeting Kaneki would force them to re - evaluate their views. They might start to question whether all ghouls are truly bad, especially when they see that Kaneki has his own moral code. This could create internal conflict within the squad as they try to figure out how to deal with Kaneki.
Harley Quinn might get really into it. She has a wild and unpredictable personality. She could start to role - play some of the scenarios from the fanfiction in real life, much to the confusion or amusement of the other Squad members. It would be in - character for her to embrace this strange new view of their world.
At first, Naruto would likely be very curious. He'd be eager to learn about this new world of Dragon Ball Z through the fanfiction. As he delved deeper, he'd start to form his own opinions about the characters. He might admire Goku's pure heart and his never - ending quest for self - improvement, and perhaps think about how he can apply some of those qualities to his own life as a ninja.
Their friends might be initially cautious. Some friends who knew how much they hurt each other when they broke up might be worried that they'll get hurt again. But then, seeing how happy they are together, they would gradually become supportive.
There could be a friend who is also secretly jealous of all the attention Alex is getting because of the pregnancy. This could cause some tension in their friendship as the jealous friend might start to act out or be less supportive than expected.
Krillin would probably be one of the first to be accepting. He's always been Goku's friend and would likely see Goku's inner strength regardless of the physical form. He might even joke about it a bit at first. Vegeta, on the other hand, would be initially shocked and perhaps a bit dismissive. But as he sees Goku's power in the new form, he would gradually come to respect it. Gohan would be very curious and would want to know how this transformation happened and what it means for their future battles.