Andrea's! Atreus went! He's never done anything like this and he let Blue dress him and he is sporting a colorful mohawk in pinks/blues/purples/yellows/black. He's shirtless but came with a bunch of body paint (and glitter) and asked people to either paint over any of his tattoos or to add their own! He got into it and was outgoing and breezed around to his different friend groups - probably mostly the Raven Cycle people, the Voltron crew and a little Eliot/Margo/whoever they adopt, but also anybody else that's his bud.
Gansey was there with the gangsey, and let his significant others dress him in some bi colored board shorts and a white polo that Blue turned into a crop top. Plus some bracelets and pink sunglasses. (and boat shoes). Not exactly his everyday wear except for the boatshoes. He didn't deviate far from his people BUT he did buy whatever truck food was around for sharing. Funnel cakes? yes.
Sydney was there with Jesse and got to bust out her purple wig and bright skirts and fishnets and looked pretty much nothing like what she does on a regular basis. She took too many videos of Jesse line dancing to use for blackmail later.
Richie was there with the Losers! He looked amazing/ridiculous and it took him like 30 minutes to really not be a nervous asshole (his jokes were a LITTLE cutting at first, and the losers would be used to that kind of nervous energy from him) but he settled in and relaxed after and there was Eddie handholding and PDA galore.
Aramis ended up there accidentally with Musketeers in tow and they stayed for a little while. He was charming and outgoing and would've talked up anyone and they look like poster boys for a blended household so A+++
Persephone watched from her balcony and enjoyed it but didn't participate, Caleb and Nesta hate people/crowds/anything with joy, Toph would have probably a terrible time with densely packed large crowds so she was at Boyd's fiddling away with metal things. And Evie is doing key research.