This is still underconstruction
On Seulgi's 20th birthday in 2014, Wendy prepared a hand-made Lifetime Best [sic] Friend Certificate for her basically professing her fondness for their friendship. And you can see on this video below how much Seulgi appreciates this. Apparently, this certificate is legally binding in some countries.
For Wendy's first solo album in 2021, she had a song called "Best Friend" singing about "expressing [sic] gratitude of a best friend". The song is originally arranged as a solo song but Wendy suggested and requested to do it with Seulgi to give the song more meaning by singing it with her best friend.
..because red velvet is joy yeri irene seulgiwendy!!
💚 💜 💗 💛💙
..and she is!! 😍💙💛
..unless it's wendy, i guess.
..and she is!! 💛💙
it's comfortable, i guess.
..because seeing each other being cute would make the other cute
#RussianRoulette2ndWin on SBS MTV The Show for 2 straight weeks
Red Velvet won a Bonsang in 29th Seoul Music Awards