I love how Terry didn't look the least bit offended when Kenny flipped the bird at him.
A part of me likes to believe he sort of saw Kenny as a surrogate son, or at least could've been. I always saw Terry as Kenny's Miyagi, and I can picture Kenny (when Dallas was still small) following Terry around. Terry (though manipulative) is more soft and sympathetic than Kreese was. Terry was probably the 'nicer' one.
Yes, Robby trained Kenny most of the time with the addition of Tory, but I'm pretty sure he was more of a brotherly figure. Terry had the mentor title because not only was he much older, but he could teach things Robby didn't know.
Like, Daniel was someone to torment, whereas Kenny's mentorship was genuine. There was a bond forming between them. Edit: Kenny and Daniel both have big brown eyes. Makes me wonder, if Daniel wasn't an enemy, would Terry have treated Daniel like he treated Kenny? Even with the coke in his system?
When Kenny flips the bird it's like seeing your child be rebellious, and while you could get mad, it's also adorable. No matter what, you'll remember them for the little kid they once were. Regardless of whether or not their anger is valid, that's your little boy/girl.
He didn't look disappointed or angered, it was more like a 'well, damn'.