Perhaps that was the moment where Tony realised that it was either now or never that he would be able to escape before Loki's mind games had a hold on him. To take off his shirt, the guards would, logically, have to let go of his arms and unlock his cuffs for at least a few seconds to pull off the shirt; it was then that Tony would fight. However, what he hadn't counted on that that was exactly what the guards were expecting; in hindsight, he should've just allowed them to take the shirt off without a fuss. The moment the cuffs were off, the mere second that Tony made a move to run, a sharp object went straight into his neck ad he was held down once again as the liquid did its 'magic'.
One by one, he started to lose feeling in his limbs until all that he could move were his terrified eyes and his speechless lips. Tony was then carried to the cage and placed on the cold ground facing the god before the door was closed with a heart-stopping clang. It was over. He'd never get out of there, not in the helpless state he was in.
Loki smiled at his brand new pet, waving the guards away once he was sure that Tony wasn't going to try and fight the sedation and hurt himself on the metal bars; the last thing the king needed, or more appropriately wanted, was a damaged pet. A smug smile graced his lips as he walked over to the cage, crouching down in front of it so that he was at Tony's eye level.
"Well, what do you think? Do you like what I had done to the place?" He was given a stern look for his troubles from the mortal, but he continued nonplussed by the reaction; it was to be expected. "Oh, come now, don't tell me you're going to lie there and glare at me all day. If I wanted a pet like that, I would have purchased a cat." The god received yet another look of disapproval before Tony closed his eyes, his lips pursed in an angry, firm line. Loki let out a huff and returned to his throne, obviously not pleased by Tony's behaviour.
He knew it would take some time to get Tony to start acting as he was supposed to, but that was the one thing he disliked about keeping pets: training them. While Loki was quite patient, he didn't like having his patient tried by something as pathetic as a mortal. Sighing out, he redirected his attention to a book; he'd have to start training another day.
Tony almost let out a sigh of relief when Loki left him be; maybe there was some chance that he didn't please the prince, so perhaps he'd be let free…or alternately be killed for his troubles. He wanted to know exactly what was expected of him to do as a 'pet', but that mean he'd have to A) swallow his pride and actually ask Loki a question and B) break his useless vow of silence, which would only please Loki; that was definitely not something he'd do willingly. Time passed far too slowly for his liking, and, he noticed after looking around a bit, there were no more clocks in the room, so not only did time pass slowly, he also had no clue what time it actually was. After a long while, Tony started to regain the feeling in his legs and arms, and soon he was sure he was able to move mostly normally. However, the man chose not to move and tried to appear as if the sedation was still acting upon him, in case Loki decided to open the cage; that didn't happen what he assumed to be hours.
Instead, Loki left the throne room and returned shortly after accompanied by a few gods, or perhaps humans; Tony was never sure how to tell the difference between the two races, however based on how some of the people next to Loki seemed somewhat nervous, he picked out the humans easier that way. The cage door was swung open and Tony was dragged out kicking and using whatever fighting technique of the limited ones he knew to try and writhe out of the strong grip. Naturally, he was sedated this, however, it was a complete sedation this time, and his consciousness slipped in a few moments.
Loki watched the once-vivacious body sag in the hold of the guards and he couldn't help but smile. Once he had his pet properly marked and controlled, well, perhaps training wouldn't be so bad after all. He allowed the guards to take his pet away with the surgeons and he resumed his place on the throne, excitedly waiting for the little operation to be over.