They'd already warned Peter that Vision didn't 'do' walls. The android had the ability to phase through solid matter. Not abiding to human customs was to be expected.
But when Peter actually saw Vision phase through the walls of the Avengers facility, the prior knowledge did nothing to lessen his fright.
"Oh… my… God! I was NOT ready for that!" Peter exclaimed, throwing his arms up in the air, as a result of being caught off guard.
"I apologize if my sudden appearance frightened you. It was not my intention." Vision apologized to Peter, who was facing the opposite direction to process what had just happened.
"It's OK…" Peter turned around and assured him, not wanting the 'incident' that had happened between them to affect their working relationship.
"Uh… Vision. Can I ask you something?" Peter asked, a little hesitantly due to what he was about to ask.
"Certainly."
"Did Mr. Stark build you? Like his Iron Man suit? Because androids aren't exactly his specialty." Peter asked, with a joke about Tony's expertise. Unaware of Vision's true nature.
"No, he did not. The body you see today, was created under the orders of Ultron. He intended to use this body as a vessel to destroy humanity." Vision informed Peter, making his eyes widen.
Possessing the ripe imagination of a 15-year-old, Peter couldn't help but be reminded him of his favourite film series; Star Wars. In Vision, he saw the Death Star; a weapon of destruction constructed to subjugate the galaxy.
"Did the Avengers defeat you?! I mean him?" Peter asked excitedly and quickly corrected himself, eager to find out what happened next.
"I was given a life of my own and fought alongside them, until every last remnant of Ultron was gone." Vision explained, silencing the usually chatty Peter. His impression of Vision had been wrong. The android was not a walking Death Star. He was much better than that.
"So, you're like C-3PO." Peter spoke, breaking the silence after a moment of reflection.
"I am not familiar with that name."
"C-3PO. He's a droid in the Star Wars movies. He was built by the bad guy when he was a kid, but then Threepio helped the rebels! Evil origins. Good droid." Peter summed up C-3PO's history for Vision, recognizing the value in the android.
"That is an intriguing observation." Vision politely remarked and began walking away.
"They're awesome movies by the way. You should watch them, if you get the chance." Peter added, as Vision walked ahead of him, still within earshot.
"I shall have to try them someday." Vision turned around and acknowledged Peter's advice with a smile.
"Really?! I didn't think you'd listen to me!" Peter exclaimed, unable to believe that Vision had taken his fanboy recommendation seriously.
"It is my intention to experience the riches of this planet. If you say they are excellent films, then I shall endeavour to see them." Vision told Peter. His faith in Peter's word making the teen smile.
I got a bit excited about the Vision name drop in Homecoming. So I decided to use Peter's love of Star Wars to make an analogy about Vision and to imagine what their interactions would be like.