I already did a rather large post with BI
here. No pun intended.
The thing with making someone immobile with their own breasts is that it doesn't take all too much size. After a certain range of size on an unwitting host, they won't be able to move because they aren't 'ready' for it. Sure it's possible to learn how to move with boobs large enough to block out your head, just not at that time. :3
Which reminds me I have that Anne BE to quickly sketch up...
