Boyfriend's toddler doesn't want anyone to help except Dad?

I don't know if I'm out of line for asking this. Not a parent currently, but I don't know a lot about kids and I wanted to know if this was normal behavior.My boyfriend (Dan)'s son Kevin seems to have learned stranger danger on his own. He's three, and if Daddy's not there, he can be fairly....uncooperative. Not saying this is a bad thing, just weird to me.For instance, if we're driving somewhere, no one but Dan is allowed to operate his car seat. Even if Dan is busy getting groceries out, Kevin will kick up a tantrum if me or his aunt tries to unbuckle his car seat straps. Yet, he also gets pissed if we've stopped and he's sitting in the car too long, so it's sort of hilarious.If we're at home and he's getting upset struggling with a toy or getting his shoes on or needs to reach something, he won't allow anyone but Dad to help. Dan was cleaning the house earlier and Kevin was starting to growl and scream and get upset because he was having trouble operating a toy gun. I went and politely asked if he needed help, but he just screamed at me "no" over and over until his dad came. At that point, he smiled widely and handed his Dad the gun.He also doesn't allow people to assist him with a bath. Even so much as running water in the tub and just letting him climb in. He was screaming earlier for someone to let the water out since he was done playing, but when I came to do that, he started angrily shrieking no again, pressing himself against the drain switch, only to happily move when Dan came over.Strangely, he lets other people prepare food for him and give him drinks. But anything else? Dad has to do it or he'll start getting angry. If Dan has to get a babysitter at any point, he's going to be screwed because Kevin will absolutely not accept any kind of assistance unless it's from Dad.Again, not saying all this is bad. Just weird. Every kid I've ever known at least lets family members help, but this kid kicks up even if his grandpa and aunt try to help, even if it's obvious Dan's busy. Gets a bit comically ridiculous when there's three people in the room willing to help, but are being denied by a pissed off thee year old. via /r/Parenting http://ift.tt/2n66BbF