Steve:

-When he looks down as he blushes in embarrassment

-His nervous laugh, his excited laugh, and just his laugh in general

-The way he reaches for your hand when he's nervous

Bucky:

-When he lightly runs his hand up and down your upper arm while his arm is around your shoulders

-That absolutely perfect smile of his that never fails to make your heart beat a little faster

-How much he enjoys cuddling

Pietro:

-The devilish smirk that seems to be eternally plastered on his face

-How often he whispers in your ear

-The wink he sends your way right before he gets himself into trouble

Loki:

-How often he gives you forehead kisses

-That sparkle in his eye when he looks at you

-His voice, especially when he's telling you stories

Clint:

-His drumming fingers when he's focused

-The look he gets when he makes something new for dinner and is hoping for your approval

-The smile he gets when you motion for him to join you on the couch

Thor:

-How happy he gets when he has made you smile

-The excitement in his voice as he tells you stories

-How tightly he holds you

Tony:

-His dorky dances in the lab

-When he tucks a strands of hair behind you ear

-He constantly mumbles to himself while he's working

Natasha:

-The way her shoulders settle ever-so-slightly in relief when you get home 

-How she always walks as softly as possible around the house even when there's no need for it

-Her mischievous smirk

Wanda:

-The way she plays with her rings while she's thinking

-When she curls up even closer to you as she's fallng asleep

-How cute she looks when she's laughing