Jacks was on his way to destroy his second heart. He brought it to the phoenix tree where you first met Apollo. The only way to erase your second heart is to pluck a leaf so the tree burns and toss your heart in. You waited for jacks to show up and he finally did. He looked cold as he tossed his heart around like one of his apples. “you shouldn’t be here.” he said as he walked past you towards the tree