Here, Take My Seat
Every time Bucky comes over to do work or look for Tony he manages to either get smooth talked into having a meal with them by Tony who'll appear out of no where. Even when there is no logical reason for a meal to be served at that time.
Once he showed up at midnight and he was talked into breakfast with them. Who has breakfast at midnight when you all have 9-5 jobs?
So, Bucky often finds himself sitting at the Stark-Strange-Banner-Quill-Rhodes-Friggason kitchen table more often than not.
His mother also raised him to be a gentleman to anyone and everyone. So, when a heavily pregnant Loki waddles in Bucky immediately notices that his chair is the only one low enough for Loki to sit on.
He's on his feet faster than he's ever moved in his life.
“Take my seat,” he says and helps Loki to get situated on it.
“Such a gentleman,” Loki says with that confusing wink again and Bucky just finds himself smiling along.
Norse Gods are weird and pregnant ones are just weirder. So, they wink at weird times.