They're the element of kindness. They moved to Ponyville from Canterlot to set up their flower shop there.
Hazel Wise (He/Him) is their older sibling. Not nearly as shy as Cotton, he's a lot more down to earth and chill than his anxious younger sibling.
He stayed back in Canterlot with their parents after Cotton moved out, and the two lost touch a little ever since. Cotton feels guilty over it to the point of avoiding him in fear he'll be mad at them (which, he isn't).