As weaknesses went it wasn't obvious. For all his youth and inexperience Kal-el had grown into a strong man worthy of his heritage. Jor-el had chosen wisely when he selected the Kent's to raise his child; that much was obvious.
What was less obvious, at least to the humans that 'Clark' had gathered around him – possibly even to Kal-el himself - was that however loving his adoptive family might have been it could never hope to entirely fill the void.
For all that the Kent's had attempted to accept their son entirely there were sides to Clark that no human could ever hope to understand. For all that he might look the same as Earth's native species; Clark was burdened with a Kryptonian soul that would have longed for companionship, and the presence of an equal.
Instead he had been surrounded by humans, with their weakness and their prejudices. Who after a lifetime spent holding back would not yearn for the company of their own kind? There was no lure more powerful than the promise of a kindred soul, and in the case of Clark a stranger even amongst his own, this would be even more pronounced.
That was the flaw in Clark's defences which Zod would use to gain entry into the other man's life, and after that his trust. After all who better to understand the difficulty of existing in a foreign world than someone from the same background? It was a tactic Clark would not see, because he would not think to look for it. The weeks Zod had spent tracking the other man had convinced him of this; Kal-el possessed a generous heart.
Not to mention the sort of naivety that was determined to see the best of people. It was an idealistic optimism that reminded Zod of Jur-el himself in the days before war and politics had turned him cold. The resemblance pained him.
That such a divide had opened between Zod and his closest friend was one of his most bitter regrets to this day. There had been a time when the idea of enmity between the two had been unthinkable. But some transgressions were not meant to heal.
Jor-el had held in his hands the power to return Zod's son, and had instead turned his back on him in his most desolate hour. Zod understood the reason; the process was untried and dangerous. To do as he had begged would have been a violation of the creed of ethics that the other man had clung to even in a world gone mad. Jur-el had always possessed an exaggerated sense of responsibility.
But that did not outweigh the sense of betrayal. If our places were reversed I would have walked into hell itself for you, Zod thought bitterly. You were simply not willing to do the same.
Still their last encounter burnt a hole into his memory. To see Jor-el brought low, to see the pained acceptance in his former brother's eyes. More than that, to see the changes that time had brought in him, a shadow of despair that had made Zod almost grateful that his memory ended where it did. That he had not witnessed whatever horror had left so pronounced a mark on a man who had once been full of hope. He had never thought to see Jor-el so aged or so exhausted.
Zod had not been sure if he would have been able to actually kill the other man, if he had been unable to get the answers he needed. In truth he still was not sure. So it had been shocking indeed to see that Jor-el had not doubted his ruthlessness for a second. What had Zod become in that other time, if Jor-el thought him capable of such a cold blooded act?
Grief and bitterness did not seem enough to justify so extreme a reaction, but there had been a world of history behind Jor-el's eyes and Zod no longer shared any of it. All he knew was that the change in him must have been dark indeed if Jor-el had truly believed that he would pose a threat to his son.
It had been difficult to keep his face blank when he had figured it out, and Zod had always prided himself on his skill in concealing his thoughts. Jor-el had been willing to die horribly (and he had honestly believed that he would) to conceal the existence of his son because he had thought that Zod would seek revenge in shedding the blood of an innocent. One who had not even existed back when Jor-el and he had fallen out.
He might have thought it a tactic to throw him, but deception had never been Jor-el's strong suit, and Zod had read him as easily as ever. It had been the first time since he had awoken on this planet, confused, disorientated and powerless that he had truly felt fear. The revelation had shaken him enough that he had ended the interrogation and the thought of killing the other man had been far from his thoughts.
Though in the end it had not even mattered. Jor-el had been killed by another and all of the questions and the empty spaces that he might otherwise have sought answers for were left painfully dangling. There would be no more questions. Any knowledge of their past had died with Jor-el and so Zod was left facing the future.
A future which in this case involved an orphan who had grown up far from home. Zod would not hurt the boy, not unless he was given a reason. Kryptonian blood was too precious now to spill it over ancient history. But that did not mean he intended to leave him alone. The thought of spending his last days powerless and surrounded by humans was unappealing and instinct told him that the boy would hold the key.
Once Jor-el had 'escaped' from confinement it had been an easy enough matter to track him, and predictably enough he had led him straight to Kal-el, although Zod had been shocked at the condition he had been in. That he should die in the arms of his son could not have been further from planned, and watching Kal-el's obvious pain, Zod had known that any chance of approaching the boy soon was ended.
Kal-el believed they had killed his father, and he would respond accordingly. Besides Jor-el's final words had been another shock and Zod would need time to consider them. Whatever darkness had existed between them, Jor-el's final action had been an attempt to exorcise it. They were no longer brother's but he would grieve Jor-el's passing. He had been a great man.
Besides it would be prudent to take some time to understand this planet and the manner of man Clark Kent would turn out to be, before confronting him. There was no way to tell if Kal-el had his powers but Zod would be surprised if he did not, and that left them dangerously unmatched. Not to mention that Clark might be all too aware of his own suspect past, whatever exactly it was that entailed.
Of one thing he could be certain; no child of Jor-el could be safely underestimated.