Oh my gosh ... sounds like my son! My thinking is that because he was my first and I was an "older" mom, we've always had a special bond. He was extremely sweet as a little boy, always hugging me, his dad and little sister. When he was about five, he used his own money and got a ring out of a gumball machine - got down on one knee and asked me to marry him - put it on my right hand because he didn't want it on the finger with "daddy's ring" - I wore that ring for about 10 years until it finally broke! (Amazing for a ring that only cost a quarter!)
As for changing - he hasn't really changed that much. He's never really gone through a rebellious stage - although, he's had rebellious "moments" he's never really caused me any heartache. Additionally, he is by no means a "mama's boy."
As an 18 year old now, he is still very sweet, we actually have fun together; he isn't embarrassed to go shopping with me (for the most part!); and we are on the same page as far as sense of humor!!! He talks to me about the girls he goes out with and just about anything. He still hugs me when coming and going; tells me he loves me; sends me silly text messages; is very caring about others and is just a great kid all around. He is a very independent go-getter type of young man and I'm sure some day will make some lucky girl a great husband!!
My daughter, on the other hand, was extremely sweet when she was little but is now 15 (need I say more?) and if someone offered me a nickel for her, well.......
Great question!!!