Spring convinced Jack to rest with her and take a break from his quest. He obliged, and lay his head on her lap, completely relaxed, but he is plagued by visions of Aku that kept him alert. Later, when he finally tried to leave, he is forced back down and he realized that he had been tricked. But as he goes to attack her the greenery rushes up around him and the illusion is dispelled, returning him back in the barren field of thorns. She watches as he leaves, and smiled enigmatically.
Spring is an enigmatic individual, her true motives unknown, although they are seemingly malevolent. Whilst enchanting Jack, she appears soothing, calm, and attentive to him, but when he attempts to leave, she suddenly turned fierce and insisted that Jack must stay by forcibly entangling him in vines. Curiously, when Jack successfully escaped from her domain, instead of became furious and dissatisfied, she smiled mysteriously and somewhat knowingly, if not also approvingly.
What and who she is are not made clear, or whom she serves, but she acts much like the faeries of European folklore: luring people into enchantments and beguiling them to stay forever.
It is possible that she was simply testing Jack and discreetly reminding him to continue his quest. This can be seen when he saw flashes of Aku in his visions when he was dozing off on Spring's lap. It should be noted that Jack formerly met the mysterious mountain monks that show him visions to motivate him to continue his quest.