Instructions
Look for Isabel in Jive Park on day 3, and Klaus will arrive to aide your search. Continue to search for Isabel at Rumba Beach, Practice Hall and Viennese Waltz Lake, and finally return to the Practice Hall. If done correctly, you'll encounter both Isabel and Klaus there. Isabel will return the Royal Tiara, and Klaus will talk to you about it.
Tell Klaus "You can fly!" when he inquires about the Royal Tiara on day 3. This will earn you +10 percent Love and allow for the "Emerald Reunion" on Day 17. This is the last interaction you have with Klaus on day 3.
Respond "No, go on!" when Klaus first comes to your room on day 17. The other choice is "Yeah, that's enough" and obviously implies that you want him to leave.
Respond "You look like a frog" when Klaus continues to reminisce with you about his past in your room on day 17. If you choose a different response, Klaus will continue to speak with you until you choose the correct response. By now, he is convinced that you were the girl who drew him a particular picture all those years ago.
Inform Klaus that you want to be his dance partner by choosing "Yeah, me too" when he asks you, which will happen immediately after you remember what you told him all those years ago.