Sasuke has come a long way, and Terry can definitely acknowledge that as a witness. He's had so much development that Terry is really proud of him for, and things moved on from Sasuke being Terry's responsibility for growth to being an actual friend that he's very fond of. Sasuke helped Terry a lot, whether he realizes it or not and Terry's really grateful for him and his everything. His words that he spoke to his Shadow (redux) were really touching and it was one of the big reasons why he made up his mind to come back.

Instead of Terry being the heart of the team since he lost that due to various circumstances, Sasuke is doing a good job and Terry will continue to support him.

I forgot, but Orien thinks Sasuke is having a lot to shoulder and thinks he needs to relax from time to time. He's also thankful that he takes care of Terry's... everything. Also the fact that he didn't run away at first sight since he's a snake was a bonus.