For the most part the motivations behind Walter's many bad choices and irrational actions make sense to me, with the one big exception of the "tequilla scene" in season 2. Giving Walter Jr one cup of alcohol on a special occasion I could understand, but it quickly gets weird after Walter pours a second one.
Hank: What you doing there?
Walter: What does it look like I'm doing?
Hank: The kid's 16. What are you, going for Father of the Year?
Walter: What are you looking at him for? We're celebrating. Come on.
[Walter Jr drinks second cup]
[Hank covers the cup with his hand when Walter tries to refill it again]
Hank: Listen, I'd take a pass on that one if I were you, okay?
[Walter pours more right through Hank's hand]
Hank: Think we've been bogarting this puppy long enough.
[Hank picks up the bottle and walks away]
Walter: Hey. Bring the bottle back.
Hank: Sorry, buddy. No can do.
[Walter stands up]
Walter: My son! My bottle! My house!
Hank: It's all right.
Walter: What are you waiting for? Bring it back.
Hank: Why don't we just call it a day? All right, pal? We good?
Walter: The bottle. Now.
Skyler: What's going on?
[Walter Jr collapses and vomits into the pool as Walter sits down silently drinks more tequilla]
I assume Walter is aware that making his son drink this much when he doesn't normally drink will probably make him extremely unhealthy and cause a big scene (like it did). Walter's dialog seems to imply this is about "control", but I don't see how this behavior increases his control or displays his masculine dominance over Hank or anything like that; if anything it just makes him look unhinged and Hank look like the mature, responsible guy (which is not what Hank normally looks like). If he was jealous that Walter Jr was talking to Hank more than him, I think he would've tried starting a conversation with Walter Jr at least once before doing whatever this was.
The very end of the scene is especially strange. Walter sits down casually and drinks yet more tequila as his son vomits at his feet. It's almost like he's saying "See that? I can make my son violently ill whenever the hell I want. Take that, other people in his life." And that makes no sense to me, unless Walter is far more deranged than I thought he was in season 2.
What was Walter's motivation for making his son drink so much and then causing a scene when Hank tried to stop him?