It's like he's going full magical girl~

Sprite has a vaguely less traumatic past than the others. Sure, he was part of the Eeveelution experiments, but Sylveons? Their evolution is based on affection and love. Sprite was the fastest of the others to evolve, spoiled and encouraged and "Loved" unconditionally. However, it was no true love, as soon as he evolved his purpose was over, and the trained scientists promptly moved on to other experiments.
Sprite was left confused and lonely, to his own devices. He was loved and perfect, apparently? But yet where did everyone go? It didn't take long for him to realise all his material gifts were meaningless. All the books and toys and food meant nothing compared to the attention of others. Oddly he never grew bitter, just incredibly eager to share with others his wealth for he saw no meaning nor worth in the things that surrounded him compared to the smiles of others. He feels a lot of guilt for having such a "pain free" growth unlike the others and enjoys baking treats and cooking meals for everyone, as food seems to be the safest thing the others all enjoy that he can do for them.

Both he and Vee (the Eevee) have an obsession with pleasing and trying to be useful which boarders unhealthy at times, though Sprite does his best to keep Vee from feeling pressured to be anything, which he himself could learn to do himself~