Both
The first time it happens, he’s in the common floor and the news is on and for some reason Tony now cannot recall they’re bringing up the battle again and footage, of the portal the black-hole – space – Chitauri pouring out – Leviathans, the mothership. Darkness and fire and thin air and silence and- he tears himself away from having leaned against the sofa’s backrest. His hand with the mug trembles he hears himself panting – Bruce approaches. Ringing in his ears he can’t hear the words forming, the concern on Banner’s face blurring. A grip on his shoulder light however is still the contact’s triggering. Next he knows he’s on his knees on the floor breath shallow, commotion loud the world’s spinning. He blinks and blinks willing things steady sees Bruce across on the ground pushing to his feet, fists clenched – he’s Hulking out, by the looks of it [that’s not good.]
He's hauled off the floor gasps- “Shh, easy,” Loki’s voice, Loki’s arm around him Loki’s grip on his bicep.
“Bruce. You okay?” Steve asks nearing slowly. Banner growls, nods, sharply exhales.
“Yeah. Yeah, good.” Steve helps him up.
“What the fuck was that??” Clint hisses Tony looks sees the archer’s dumbfounded, glaring at him.
“Loki,” Thor calls tone stern – Steve adds:
“You need to tell us what you did, right now.”
“Well isn’t it obvious, Captain?”
“Undo it,” Clint demands.
“I cannot.”
“Can’t or won’t?” Romanoff asks.
“Both. Now if you don’t mind, someone ought teach Stark how to control his new powers,” he nudges the perplexed and still slightly panicking man in his arms forward, towards the lift they ignore all calls.
Door slides shut, Loki speaks up: “To be frank I hadn’t predicted that outcome. Most of them, save heightening your strength.”
“Loki what did you do?” he asks this time and he wants the full answer. The three seconds it takes the god to answer are too long.
“I, instilled you with a fraction of my lifeforce. More than a fraction it would seem.” Up at him Stark stares bewildered. He’d asked before and Loki would joke and quip and he’d let it slide because he was grateful and he didn’t like to pry not when it came to Loki he didn’t like bothering him – because everyone and everything bothered Loki, except him and Tony took pride in that.
And Tony’s confused now and dumbstruck because that, sounds of far more a gravity than he’d first assumed – why, is the question caught at the tip of his tongue as the lift parts and Loki settles for a loose grip on his arm to move them forward, into the sanctuary of the lab’s four walls where the tension ebbs swiftly from Tony.
“Let me see now,” Loki takes him by the shoulders. Cool hands rose pressed light against the sides of his face and Loki’s eyes shut. Tony wanted to tilt closer. His own closed as Loki’s warm magic through him coursed and he sighed. And when he opened his eyes Loki was smiling, such fondness in his twinkling greens, the glee in his voice. “Well Tony Stark. I think you’ll like this.”