It was so sudden, Tony had no idea where it had come from or how to find it. One moment he was a normal guy flying around in his Iron Man suit, just doing a few flyby's to make sure things were quiet. The next minute he was feeling a sudden pain at his tail bone and on top of his head. Soon, it had gotten so bad he had to get out of the suit.
Tony landed in a back alley so not to attract attention. The moment he stepped out of his suit and caught glimpse of himself from a reflection in a dirty window he nearly screeched. He had a pair of furry ears and a dark furry tail sticking out of his ass. Where the hell had these come from!?
"Jarvis, what happened to me!?" Tony whispered harshly to the suit of armor still standing next to him.
"My scans indicate that your DNA has been altered. However, I wouldn't worry much sir. The report suggests that the effects are deteriorating at a steady rate. My diagnosis is that these effects should only last 24 hours." Jarvis explained to him. They could try to find out how and why this happened, and find a cure. But to be honest the effects would wear off before they'd be able to synthesize anything to reverse the effects.
"Great, so I'm a neko for a day..." Tony grumbled, looking around. "Alright, just take a sample of my DNA so we can study this later. In the meantime, I'd just better get somewhere safe to wait this out." Tony said and looked around.
"Might I suggest Sergeant Barnes, sir? He is very close and the two of you have been getting along quite well." Jarvis suggested as the suit came over to take the sample Tony wanted. "And besides, you do have a crush on him."
Tony looked up at the suit, looking flabbergasted at the AI's insinuations. "Who told you!?" He demanded
Jarvis looked at Tony for a moment, mustering the best stale tone he could. "No one, sir. It is very obvious." Jarvis guided the suit to grab Tony to fly him to Bucky, where the super soldier was settled in a safe house. He would've opened the armor for Tony but there just wasn't room enough for the ears or tail without harming him.
A moment later they landed near the safe house Bucky had taken up in. Tony carefully climbed the steps, arms wrapped around himself feeling so out of his element. He reached up and knocked, looking around trying to make sure no one saw him and his new accessories. When he heard boots coming to the door he spoke so Bucky knew who it was behind the door. "It's Tony." He said. He felt bad for just kind of, showing up. But he didn't know what else to do. When Bucky cracked open the door Tony looked up at him, tail swishing a bit behind him. "Sanctuary?" he asked, looking like a pathetic little kitten, ears down and dejected.
I Am Iron Man.