Time was not a plaything. On the contrary, guarding it was a grave responsibility.
If Tony Stark grasped the full import of Stephen’s position as Sorcerer Supreme, he certainly didn’t evince that comprehension in their first conversation. Or their second. Or their third. So when Stark - Tony - once again dismissed Stephen’s supposed “mystic mumbo jumbo” while peering at the guts of the Maw’s ship, Stephen decided one well-placed magical zap was just what the doctor ordered.
“Ow!” Rubbing his head where he’d bumped it against an instrument panel, Tony turned and fixed Stephen with a glare. “What the hell?”
“What’s that you were saying about my ‘mumbo jumbo’?” Stephen asked coolly, privately relishing the chance to put the irritating popinjay in his place.
(Irritating popinjay. Irreverent prick. Those were his perceptions of Tony - then. )
Tony, however, refused to be cowed. Instead, he folded his arms and lifted his chin, defiant. “If you keep spanking my ass, Merlin, I’m going to start taking your propositions seriously.”
“If only.” Stephen recognized Tony’s joke for what it was but elected not to rise to the bait. Even though the autopilot was engaged, understanding the vessel that was, at the time, flying them to Thanos' home planet was far more important than winning a verbal fencing match - no matter how satisfying such a victory would be. “Just figure out how to steer, Stark, and keep your wisecracks to yourself.”
“You’re not the boss of me.” But Tony did in fact return to the task at hand, slithering back into the ship’s drive. “I hate magic,” he grumbled sotto voce.
No: Tony didn’t understand. But as it turned out, neither did Stephen. Not fully - until now.
Time was not a plaything; the lure of its deepest secrets was a dangerous snare.
Tony was a volatile element; the media coverage of his exploits over the years had made that abundantly clear. As towering as his intellect was reputed to be, the evidence - for instance, the fact that his Malibu mansion now lay in ruins on the coastal shelf - suggested he was driven more by gusts of passion than by his smarts.
Peter, meanwhile, was gifted enough - and exquisitely polite and well-meaning - for an apprentice. (Yes, Stephen eventually learned the official nature of the boy’s connection to Tony - though it still seemed, to him, that his original judgment that there was a familial tie was correct.) But Peter was also callow - and perhaps a little too desperate to prove himself. Would that lead him to be careless? That he’d boarded the ship at all - and had apparently done so against Tony’s expressed wishes based on the two quiet but fierce and rapid-fire arguments Stephen had overheard when the pair thought they weren’t being observed - left that question disconcertingly open.
As for Quill and his companions? Also hopelessly - and maybe perilously - unpredictable.
As he listened to Quill and Tony bicker, Stephen grew more and more uncertain about their chances. He’d allowed Tony to take the lead because - in momentary flashes, when the persona dropped - he’d seen something sincere in the other man’s eyes - a clarity of purpose and an undercurrent of fear - that deserved to be taken seriously. But Tony’s temperament appeared unequal to the task of wrangling their ersatz team into some semblance of unity. Indeed, it wasn’t long before the engineer let his impatience take control. And Quill's own insecurities were only making things worse.
Stephen succumbed to temptation to assuage his doubts. He needed to know if Tony was right to allow the ship to bring them to Titan instead of turning back. He needed confirmation that they were on the proper course. So he did what he'd been admonished never to attempt: he looked forward into the time stream.
Fourteen million, six hundred and five different branches - and he found only one in which Thanos was beaten.
They had one chance. But at what cost?
Time was not a plaything; having wielded its power, Stephen was forced to condemn a man to die through his own deliberate inaction. And now he had to look into the eyes of Tony’s comrades-in-arms - into the eyes of Tony’s wife - and come to terms with that terrible truth.
Tony would say that his life for billions was a fair deal. That was something Stephen learned in his travels through the stream. Millions of failed tributaries began with Tony successfully convincing Stephen not to give up the time stone. Millions more began with Tony sacrificing himself in other ways.
True: there were alternative paths that began with Tony choosing to abandon the fight permanently after Thanos’ victory - but these were far fewer in number. Because Tony Stark, evidently, was man unlikely to just let things go. Whether that was an artifact of his pride, his stubbornness, or his guilt - or some combination of the three - was hard to say.
And there were other things Stephen learned about Tony. In every branch in which Tony survived both the battle on Titan and the long trip back to Earth - including the one future that was now their reality - he came home a broken man. Many times, Stephen watched Tony cry for Peter - and for others he barely knew. Many times, Stephen watched Tony curse the “Bleecker Street magician” who’d surrendered to make sure he lived.
Stephen even saw Tony’s daughter - and how tenderly Tony held her in his arms. That shattered his first impressions completely and replaced them with something new. That was the revelation that made “Stark” Tony .
Stephen’s power had given him an awesome privilege - and an awesome burden. It had also taught him something profound and absolutely essential. And looking around the Quinjet at the others - taking in their various expressions of grief - only confirmed the lesson.
Thanos was wrong not simply because he murdered on a planetary scale and not simply because he’d stolen his victims’ right to choose. He was wrong because he saw each person as a means to an end. As a number on a ledger. As dispensable.
And Tony was wrong too: One for billions was an awful - if necessary - trade.