Things about Griffin Cross that are irrevocably true:

Because of the serum, his metabolism is too fast to get drunk on human alcohol. He drinks whiskey because he enjoys the taste. He never wants to drink Asgardian liquor again after what happened the first time.
He quickly loses his patience with most people, but he always seems to find a little more just for you. If he knows you is purposely pushing his buttons, though...
Seeing you wearing one of his t-shirts around the house always gets him a little riled up.
He is a firm believer in 'save a horse, ride a super soldier'. He pulls you into his lap every chance he gets when the two of you are alone.
He wants you to be able to defend yourself when he's not around, so he has started training you and sparring with you. Things always seem to get a little heated in the best way...
He has a lot of trauma from what HYDRA made him do as the Winter Soldier (IYKYK), so he is still figuring out what he enjoys when you're together. So far, he likes it slow and intimate the most, but he enjoys exploring things with you.
He loves to trail his fingertips and lips all over your sk-n. He thinks you have the softest sk-n.
If he's when you shower, he ends up in the shower with you more often than not.
You're his favorite way to de-stress after a mission.
He loves to play with your hair when you're near. Either playful flirty tugs when you're in public, or twirling it/running his fingers through it while you're cuddling or watching a movie.
Everyone thinks he looks grumpy and mean, but he always smiles when he's with you. You tease him about being a teddy bear.
He is always worried about hurting you with his enhanced strength, so he's usually gentle with you. But, if you sass him enough, he will manhandle you just a little.
He is very communicative when you're together. He talks you through it and praises you: "That's it, just like that... That's my girl." etc.