Jealousy
He is not a jealous person.
Jealousy is always an ugly feeling and has a bitter aftertaste.
But he can't shake that annoying itch in his head as he watches Clint talking to Marc Spector - better known as Moon Knight - who is invading Clint's personal space as if it were natural. He is aware that Clint knows no distance. Clint tends to orbit around each person like a moon, while the distance should always being the sun and earth. Moon Knight doesn't seem to care either.
“He is an old friend and colleague. We were in the West Coast Avengers together," Clint had said before the mission began, when they saw the other man who had the exact same goal. The statement that they were old friends and colleagues made the itch start. For Clint, that might mean, “We once had lunch together at a Shield base and talked about dogs,” or “We once spent three months in Alaska and had sex.”
In the twenty minutes of working together, there was an old familiarity. But this is normal when you have been in a team for a long period of time. If one of the other Howlys were standing in front of him, that familiarity would also be there. It's the conversation now and the apparent ignoring of the personal space that increases the itch. Clint is someone who talks with a lot of gestures and Moon Knight seems to respond to that. A touch on the shoulder. Another on the forearm.
And as much as Bucky tells himself it's just friendly, the bitter aftertaste remains.
He looks at his phone to check the time and realizes it's close to midnight. Sighing, he puts his phone back in his pocket and when he looks up, Moon Knight whispers something in Clint's ear that makes him laugh. However, it is one step too far. The bitter taste turns into something sour and he comes closer.
“Clint-” Bucky begins, his tone trying to be neutral. They both look at him, although he can't see Moon Knight's face. “We should get going. You still have to walk Lucky and Alpine will get mad if she doesn't get another nighttime snack and I don't want to buy new pillows again."
“Aw pillow,” Clint sighs, stepping towards Bucky. “We should definitely do this again,” Clint adds, looking at Moon Knight, whose mask shows no reaction. “Sure,” Moon Knight replies in monosyllables and Clint grins happily. "Awesome. Have a successful night,” Clint says, taking Bucky by the hand. Bucky looks at Moon Knight for a moment, who is still standing in position and looking at them. Bucky can't interpret it properly. He hates it when he can't see a face, so he turns away and focuses on Clint, who's talking about getting a pizza somewhere.
While Clint chatters away, Bucky can still feel Moon Knight's eyes on him. There's a slight burning sensation in the back of his head. But when he looks over his shoulder, the alley is empty. He squeezes Clint's hand tighter and takes a deep breath to relax himself.
He is not a jealous person.
But sometimes, well...apparently he is.