Sky and Syd shared a life together before the series, and though nothing much is ever said about it we can see that they were at least friends, maybe even more. But as time went by things changed, whether it was just time, or the stress of their lives that seemed to pull Sky away from everyone else. The two were still friends, but not very close anymore, as Sky changed they just couldn't understand each other.

But through their time as rangers, they slowly seemed to find each other again. Syd was the only one that could consistently get under Sky's skin, sometimes annoying him but more often that not simply amusing him. They share many looks, many moments, and the chemistry they had was undeniable. She got to him, it's not hard to see where they could go, together, from there.