Will this overbonding lessen as he starts to realize he has a permanent home and we all love him?

Probably not, at least not all by itself. First, I highly recommend a book by Mattie Sue Athan titled "Guide to a Well-Behaved Parrot," which explains strategies for dealing with this problem in depth. Most of what I'm about to tell you comes from this book.

In the meantime, here are a few quick suggestions:

1) Do not reward Sassy for aggressive displays and/or attacking other people. Particularly, don't laugh. When he attacks any-one or punishes you, scold him and return him to his cage for a few minutes of "chill" time.

2) Have Sassy's most favorite foods and treats offered to him only by the "non-favored" person. If Sassy likes to bathe or be misted, have only the n-f person do this, also.

3) Have the n-f person take Sassy into a strange situation by themselves, such as a pet store or bird club meeting. When everyone and everything around him are strange, he will probably turn to the n-f person as being the only familiar thing in the environment.

4) If possible, have the n-f person be the only one that gets Sassy out of his cage. I.E., he doesn't get to come out unless he is willing to step-up for someone other than you.

5) Anything unpleasant, such as grooming, returning him to the cage, bathing if he doesn't like it, etc., YOU do.

6) Start working with Sassy on "nurturing dominance." YOU are the head of the flock, not Sassy! Lower the cage and the playgym so that Sassy can't get his eyes above yours. In parrots, height is dominance. Start doing lots of step-up/step-down practice. Do NOT allow Sassy on your shoulder until/unless he has stopped displaying aggressive behavior. It would be better not to allow Sassy on your shoulder at all until the overbonding is corrected.

P.S. A side note: if you have a shy or nervous parrot, one way to help correct it is to deliberately raise the cage and/or playgym and get the bird at or above your eye level.

An unpleasant but necessary warning:

Parrots do not/can not realize how fragile our skin is. Mated pairs and flock members "nip" each other routinely without damage because the feathers protect their skin. What would be a mildly punitive nip from one parrot to another can put YOU in stitches, especially if Sassy is on your shoulder and can reach your face. If you can't keep Sassy off of you altogether, at least don't touch, hug, kiss, etc., anyone while he is on you, as you could be severely bitten.

Lulu bit John's daughter in the face on Memorial day, and she is a female! (Luckily Lulu doesn't generally draw blood - Mandy was only bruised, but it was a wake-up call for John and I.) Parrots that do this don't MEAN to do the damage that they do, it's a combination of natural instinct and ignorance of our fragility.

However, the victim is still injured. I know of a lady whose pet Goffin's almost took out her eye and caused her to require 20+ stitches because her husband came home from work and kissed her while her pet was on her shoulder. The bird was immediately sold to some people who know their stuff and is now a docile and well-behaved pet in the new family, but the woman will wear that scar the rest of her life. Don't be scared, just be respectful and careful.