[Big Bang Theory]Castiel had always thought that humans were mysterious and complicated beings but he never thought acquiring a vessel was that hard. He had explained as much of the process to his vessel as was understandable to a human but Sheldon Cooper continued to resist. The human contradicted him on the most basic principles and continued questions. The answer that the string theory was as wrong as the loop quantum theory had angered the scientist to a degree Castiel couldn't understand. The angel basked in the knowledge that even if Sheldon resisted he still had Missy Cooper as a possible vessel.
Two and a half Men
[Two and a half Men]Charlie Harper was a sinner and he was aware of that, enjoyed it even. Since he had the idea that he would not qualify for heaven he should enjoy his life as much as he could. Surprisingly it didn't take much for Castiel to get him to agree to accept the burden and privilege of becoming an angels vessel. Just a simple question and Castiel took his new body and did gods work. And if the human had been drunk at the time, as vessel he was guaranteed a trip to heaven. Castiel decided early not to visit Charlies heaven.
CSI: Crime Scene Investigation
[CSI: Crime Scene Investigation]Castiel watched the actions of his future vessel carefully. It was so interesting what humans were willing to endure, what they chose to endure without any need. What amused them. Grabbing this opportunity the angel knew he would have a lot of questions. Lady Heather obviously enjoyed her work and knew what she was doing and how far she could go. She was intelligent, well-spoken, had a wide variety of knowledge and more insights in the human psyche than many others. She was the perfect vessel. Castiel looked forward to this. Having her as his vessel would be most educational.