Final answer:
The provided information does not mention characters Vanessa or Aimee, nor does it contain content about the ideas mentioned in the question. More context is needed to provide an accurate answer.
Step-by-step explanation:
The provided information does not include any details about a character named Vanessa or Aimee. Therefore, it's impossible to answer what idea Vanessa put into Aimee's mind about her parents. The information pertains to Caitlin's visit to Madrid and her experiences with feeling isolated due to cultural differences. There's no mention of Vanessa, Aimee, or any idea being shared about parents. To properly address the question, additional context or content from the source material, such as a book or a story, where these characters exist, would be required.