In my headcanon of a future for the FIM characters, I envision Spike and Flurry being close friends and she would refer to him as “Uncle Spike” sometimes. He’d be assisting her a lot on some of her adventures much like we see with Spike and Twilight in the current show. Now that Spike is much bigger, he’d serve as more of a protector in cases of trouble but is still there for her like he was for Twilight when he was a baby dragon.
MLPFIM © Hasbro