In the dusty village of Griffonstone— or at least what was left of Griffonstone— Gallus did not have many friends. As a matter of fact he didn't have any friends to speak of. That was the way of Griffonstone after all; you were only as valuable as the bits you had to your name, and only as so far as a means to acquire value. Things like that do not make it easy for an adolescent griffon, especially one as broke as poor Gallus. And of course, let's not forget his natural plumage somewhat closely matching the wonderbolt uniform made him an easy target for mockery and bullying by other griffons who either did not know or care that their ruined country was by no means an enemy of Equestria. To top it all off his own family thought he was a burden and a responsibility forced upon them that they'd rather do without. No griffon would ever care about him.
Or at least that was what he was convinced of until after an exceptionally bad day he turned in desperation to his big sister Gabby. He ranted, raved and screamed all his frustrations at her, talking about how he hated Grandpa Gruff's lack of sympathy for him or the rest of the family, how he hated Gilda not stopping and even joining in on the bullying he got and just how sick he was of her babying him all the time. He was expecting her to snap back and make him stay outside overnight— it's what Gilda would have done anyway. And yet through his long winded fit Gabby never interrupted him or yelled back, she just sat and listened intently. When Gallus ran out of breath and things to say, his big sister just smiled and pulled him close and tucking his head underneath her chin. When she reached around his back with one arm, Gallus was confused. "What're you doing?" he asked.
"Aw c'mon Gallus, don't tell me you've never heard of a hug!" She answered with a cheery laugh. "I wanted to be nice to you because I know just how mean everyone else is, but I'm sorry for babying you. are you gonna be okay?"
Sniffling and still confused by the affection, Gallus half-heartedly wrapped his arms around her to return the gesture. "You… just wanted to be nice to me? Why didn't I know about this sooner?"
Gabby didn't bother answering the question right away, at least not until she knew he didn't want to let go yet. "I dunno Gallus, I thought it was obvious? You're much more important to me than some stupid gold coins."
-----
The picture took me about three hours. The little story for it took me two. Gah, this is what happens when you've got youtube on the other monitor grabbing your attention.
Also this takes into account a head-canon of mine that Gabby, Gilda, Gallus and Grandpa Gruff are all related. make of that as you will.