@NoNarnas - when ds1 was going through the tantrum stage, I did something arguably much worse than giving him juice.
He’d had a 90 minute tantrum the night beforehand, and it wasn’t yet 9am, and he’d been tantrumming for 45 minutes. I was heavily pregnant with ds2, and had reached the end of my tether - so I was on the phone to dh, in floods of tears, because I couldn’t take any more, when it went quiet. Suspiciously quiet - so I rang off, and went to see what had stopped him screaming.
I found him by the kitchen bin, eating the leftover tortilla chips that we’d thrown away the night before - which is bad enough, but not the worst bit.
I knew that, if I took him away from his oh so tasty snack, he would start screaming again, and I couldn’t face it -so I let him carry on eating, and waited until he had had enough, and wandered away - then I emptied the bin, and found somewhere to put it, where he couldn’t get at it again.
Thankfully he was not ill, and giving in on that occasion didn’t ruin his character! It is a story I shall be dining out on for the rest of his life though!
. And it means that, whenever some frazzled parent is fretting about being the worst parent ever, I can relieve their minds.
If I were you' I would give him the juice, but gradually dilute it more and more, until it is the barest hint of flavour - do it slowly enough, and he will not notice.