I can't decide what's my favorite part of this anecdote, because confirming that Flins can't even get tipsy because his flame just instantly combusts alcohol means:
First, all those times we see Flins drinking or talking about drinking were actually just for love of the game. He confirms here that he's not drinking because he enjoys savoring the sensations or tastes; he doesn't even get a pleasant buzz out of it... He's almost certainly doing it because it's the fastest vehicle in Nod-Krai for social interaction. Humans like drinking, so Flins drinks to have an excuse to be near them.
Just like Durin, who realizes that drinking would be one of the fastest ways to endear himself to Mondstadters:
Flins has clearly figured out that the way into humans' hearts is to make sure they're happily tipsy 90% of the time.
From all the way back in his character teaser, we see Flins using a chat over drinks to get what he wants out of Ulman (he wants an excuse to lead Ulman to safety because he knows the Wild Hunt are active that night):
Illuga points out that Flins uses drinking just as a means to further social interactions:
We get to see Flins using alcohol as the basis for his friendship with Demyan at the Flagship:
(By the way, he's good enough friends with Demyan that Demyan asks Flins to take over bartending duties at the Flagship when Demyan has to go out of town--Flins was tending a whole ass bar as a side gig for his NPC bro just for the hell of it. Flins really loves people.)
Even his "Favorite Food" line focuses entirely on how Fire-Water can make other people feel; while his "Least Favorite Food" line emphasizes that eating/drinking for him is essentially an entirely social endeavor:
And of course, spending copious amounts of time drinking with Varka, not for the drinks but for the company:
There's just something so endearing about the picture this whole thing paints--despite claiming to not be a very social creature, Flins has put in the effort to become a whole connoisseur of fine wines and spirits because doing so makes it easier to gain acceptance from humans, makes it easier for him to form friendships with people.
Flins isn't Varka's drinking buddy because he likes drinking; he's Varka's drinking buddy simply because he likes having a buddy.
It even gets more charming when coupled with Varka's teapot dialogue, which reveals that until the alcohol starts flowing, Varka is actually a bit socially awkward too and doesn't know how to carry on conversations that don't fit his normal patterns of interaction:
(They're both depending on the beer to help them make friends lol.)
For Flins, just like with Durin, the idea of a magical creature working hard to understand human customs, wanting to learn how to fit in, and finding joy in just being welcomed to spend time with others... So, so, so cute.
Second though! Even though that whole aspect is adorable, the other part of the anecdote's reveal just has me in stitches...
This anecdote confirmed that alcohol's only effect on Flins is as fuel... which makes all his drinking with Varka soooo much funnier in hindsight.
Like no wonder Flins is so smiley and giggly every time we end up seeing him out drinking with the Grand Master. Pouring that much alcohol on a fire would basically be the human equivalent of knocking back a six-pack of Monster energy drinks and then trying to interact like you're perfectly-fine-totally-not-vibrating from the adrenaline rush. Dumping a whole bottle of alcohol on a fire makes it go VHOOSH, you know???
Flins is probably getting wired as hell every time he hangs out with Varka. 😂😂😂 He's shotgunning a whole line of Five Hour Energies and then going "Oh my god Grand Master, you're sooo funny."
A cocktail or a beer flagon or two with other Lightkeepers or Nasha Town residents to fuel a pleasant conversation is Flins's regular modus operandi, and then Varka comes around with his 30-gallon barrels and it's like
Thanks for this random stock photo, Food Republic.
Maybe Flins can't "let loose" and get drunk like humans can, but the idea of a fire struggling to contain itself while blazing from the all fuel he gets every time he sees his newest "drinking buddy"... Trying to still act gentlemanly, aloof, and cool-headed while his flame is flickering all over the place from all that extra energy... Ahhh, this is really adorable too.
B-But then there's even a third aspect I love, because what you do you mean Flins and Varka have never had a single drink together that qualifies as "juice":
Yet Flins just... happened to have Wolfhook berries on hand? You never drink juice together... but you're ready to make juice... at a moment's notice...?
The fact that Flins would have had to go out of his way to get Wolfhooks for Varka is already obvious and sweet in its own right, but when you think about it even harder, it just gets even more adorable: Flins went out of his way to get the Wolfhooks without even knowing whether he'd have a guaranteed chance to use them. The fact that he just had them on hand the moment this topic came up means he had already been ready for that situation. He bought the Wolfhooks in advance and was just waiting for the chance to share them.
Flins picked something up that he knew Varka would like and then literally had to manuever the whole situation just to work them into the conversation. What if Demyan had never asked him to tend the bar? What if the topic of talk just hadn't turned that way? What if Varka hadn't asked for something different than usual?
Would Flins just have had to figure out some completely different way to get the Wolfhooks to Varka?
Despite it being unusual and outside their normal pattern, Flins knew that Varka would like the Wolfhooks, so he bought them just like that, plan or no plan. Even putting aside shipping, this goes to show how generous and kind Flins really is. He cares about the people he spends time with and wants to make humans feel better when they're down. Flins genuinely appears happiest when experiencing joy vicariously--other people being happy seems to be what makes him glow.