I've been on a Annie and Sunstreak kick for some reason lately XD
In Canon Sunstreak is very subtle when showing affection, mostly using words more than physical means unless started by Annie. They're both very private about how they show affection towards each other (both cuz of their current situation regarding her family, and cuz they're just not fans of PDA).
But man… There's some deep thoughts going on in that noggin. XD