|For other uses, see Cameron Klein (disambiguation)|
- "No, stop! Please! No! Make it stop! Please, make it stop!"
- ―Cameron Klein[src]
Klein was one of six subjects administered GH.325 and observed by Coulson and Dr. Goodman in the Guest House. Just as the others did, Klein began writing the alien symbols as the DNA of the G.H., from whom GH.325 was derived, began taking over his mind. Coulson conferred with Goodman and she suggested using the Memory Overwriting Machine to replace Klein's memories so that he could live a normal life. As part of the new life Klein was given, his name was changed to Hank Thompson.
One of the projects he and his son did together was play with model trains. The urges to write the alien symbols still came to him but he subdued them by making the train tracks loop and curve in those shapes.
In 2015, while Thompson was playing with his son, Sebastian Derik came to him. Derik was also a participant in Project T.A.H.I.T.I. before Phil Coulson shut it down. Derik tied up Thompson's wife and son as Coulson came to Thompson's house. Thompson told Coulson that he knew nothing about the alien symbols and that he just wanted to be left alone. At gunpoint, Coulson attempted to press the issue. Thompson told Coulson that he already told the other guy the same as he is saying now. As Coulson realized that Derik was there, he was knocked unconscious.
Coulson was suspended from a ceiling beam while Thompson was tied up. As Derik and Thompson argued about Project T.A.H.I.T.I. and the alien symbols with Derik holding a knife to carve the symbols into Coulson, Thompson freed himself and attempted to rescue his family. Derik threw the knife at Thompson and he caught it before it hit his face. Thompson then threw the knife at Coulson's noose, cutting it.
Thompson and his family ran to the nearby road as Coulson and Derik struggled. Driving by looking for the Thompson residence were Skye and Alphonso Mackenzie; they knew that Coulson went there, seeking Thompson. He told them that he needed help and they went to his home to stop the situation.
Loving Civilian Life
Director Phil Coulson took Thompson to the Playground and told him about his past. Coulson then offered him a place with S.H.I.E.L.D. again. Thompson declined because he loved being a civilian, his job and family, and the normalcy that came with it. He then gave Coulson his business card and was blindfolded and escorted home. 
- In the comics, Cameron Klein is a technician working for S.H.I.E.L.D., and the grandson of Stanley Klein, a United States Armed Forces private rescued by Captain America and the Howling Commandos during World War II.
- Another S.H.I.E.L.D. agent of the same name is based on the same character.