The following contains spoilers for Super Sons #13, by Peter Tomasi, Carlo Barberi, Gabe Eltaeb, and Art Thibert.
Since the beginning of Super Sons, Superboy (Jon Kent) has only interacted with one part of Damian Wayne's family: his dad. That's to be expected, since Batman and Superman work together all the time, and he and Robin basically only know one another because of that bond their fathers share. Over the past year, Super Sons never brought up Damian's mother, Talia al Ghul, and as it turns out, there's a reason for this omission. The title's new arc for the young heroes, titled "The Parent Trap," deals with Robin's heritage head-on -- for better of for worse.
Since Robin joined his father's crusade, it's been made clear that the al Ghul family is incredibly messed up, and that Damian is lucky to have a father who wants him to be a person rather than a weapon. Whenever it comes to the young Wayne, the al Ghuls seldom have a plan for him that is formed out of love; following his death, Ra's stole his body with plans to make more clones of him, for example, and just like her father, Talia herself has a very twisted idea of affection for her child.
The relationship between Talia and Damian has always been incredibly complicated; sometimes she'll put out a contract hit on him, other times she'll warn him about his grandfather's incoming wrath. Ever since DC's Rebirth started two years ago, she's shown up here and there in books featuring both Batman and her son; most recently, the Dark Knight and Catwoman fought her to gain access to Holly, a friend of Selina's who sought Talia to escape being tried for killing hundreds of terrorists. Now, for her and her son's first meeting since before Damian formed the Teen Titans, Talia has opted to try and whisk her son away on a mission with her personal army.
Of course, it's not that simple. Now that Damian and Jon are a package deal and go to school together, the Boy of Steel gets his first opportunity to meet Talia when she tries to kidnap Damian and puts a blade to his throat, something the Robin doesn't even have the energy to get worked up about. It would be putting it mildly to say that Jon's shocked to learn his friend was an actual killer; he never thought that Damian had the sunniest of childhoods, but he always took that as simply being Batman's kid and being "occasionally mean." Never once did he think that his teenage friend was an assassin trained from birth to kill.
The news that Damian is the heir to the League of Assassins is understandably upsetting to Jon. The boys just found themselves face to face with a potential future where Superboy grows up and kills millions to stop an adult Damian, and to make sure that doesn't happen, they've sworn to protect each other from the unfortunate fate that could befall them. Damian argues that his time with the Assassins was a lifetime ago, but Jon is now learning a completely new side to his best friend.
Super Sons is officially ending in May with an arc titled "End of Innocence," and that title likely encompasses this arc as well. Jon's never been dumb, but the events that he's been through in the last couple of months -- not just the events of Super Sons of Tomorrow, but also being manipulated by Manchester Black, failing to stop a planet from being destroyed -- have clearly changed him. As the Boy of Steel and the Boy Wonder find themselves at the beginning of the end of their partnership, Jon will certainly have grown greatly from the experience. These are all things the boys will figure out together, but first, they have to stop Damian's mom from trying to kill Lois Lane.