With the obvious caveat of 'this show's so fucked I can't be sure of anything', I'd say there is zero chance Walt poisoned the kid. The thing that made it obvious to me was how Gus' demeanour changed from when Jesse said the kid was sick, to when he said he was posioned. He literally went from 'get back to work' to 'don't worry about this batch, come back when you can'. Gus' track record with kids is far from exemplary, so I doubt he all of a sudden cared about this one in particular, simply because he was poisoned versus being sick. Seems more likely that he wanted to appear sympathetic in order to solidify Jesse's suspicions about Walt doing it, since he's that much of a psychopathic mastermind. Also think Jesse tipped his hat too much by telling Gus he knew the kid was poisoned, and that's why Gus was all suspicious about his car. Still a bit unbelievable he would leave his car unattended in a situation like that, but whatevs. So how about Walt pulling a Fance and just letting what's coming, come? I mean, there's 'taking the consequences that are coming' and then there's 'sitting at home staring at the measly six shooter, even considering offing himself'. Might as well tied his underwear to a stick and waved it around too. 'Over his head' doesn't seem descriptive enough, he seems truly helpless at this point. And aside from being a bit suspicious, staying at home by himself is selfish, too, because what the fuck is his family (ie-Skylar) supposed to do if they were to kill him at home? I know they'd blame the cartel, though Hank doesn't buy that, but what if they were to find the money in the crawl space? And if they killed him but left his pistol, the DEA would probably think twice about why the brother-in-law whose excuse to avoid protection was a car wash was found murdered in his home holding a pistol. Anyways, I'm rambling. I just love how if this were any other show, ending it this week would be stellar, and it seems impossible to make another season, yet they're totally going to. Maybe Hank's baby will get involved somehow? Pull a Maggie from the Simpsons? Eh? Eh?