Adult adoption

Originally Posted By EdHow do I adopt an adult? I'm a 54 year old male. I have a 24 year old friend who is like a son to me. His birth dad has been deceased since he was a kid and he is astranged from his mom. He has never really had a father figure in his life until we met. I love him as if I was his birth father. We even look alike. Somebody, please help. I really want to be his dad.