the fact they were 4 and still to this day he's still randomly manipulating people just makes it look like a core character trait which is why i don't understand it. There doesn't seem to be any reason or motive for him to just manipulate everyone randomly but he does.
also i never got dave using tyson as a crutch. More he just follows whatever tyson is doing like a little brother does to a big brother even hoss says dave only looks at tyson with adoration. Dave seems more like a leaf in the wind rather than 'I NEEED him or i'll fall apart' but then again loosing a brother or anyone close can cause you to fall apart