Grimes and Elon welcomed their first child, X, in May 2020. "Mom & baby all good," Elon tweeted at the time. Later that week, Grimes explain the significance of her child's name on Twitter. "X, the unknown variable," she wrote. "Æ, my elven spelling of Ai (love &/or Artificial intelligence). A-12 = precursor to SR-17 (our favourite aircraft). No weapons, no defences, just speed. Great in battle, but non-violent + (A = Archangel, my favourite song) (metal rat). I think it sounds like the name of the main character in the story. I hope he vibes with that. OK, going back into the pain/ beauty reverie for [some] time, just came on to add my thoughts. Peace to all."
Grimes and Elon began dating in 2018 and made their debut as a couple at the Met Gala that year. In September 2021, Elon told Page Six that the pair were "semi-separated" but remained friends and were still living together. Then, in a December 2021 interview with Vanity Fair, Grimes said that she would "probably refer to [Elon] as my boyfriend, but we're very fluid. We live in separate houses. We're best friends. We see each other all the time."
Yet they ran into trouble with that name due to California law, which specifies that names can only contain letters, not characters. Grimes later announced in an Instagram comment that they'd changed their son's name to X Æ A-Xii, replacing 12 with numerals, per People, but a birth certificate obtained by TMZ revealed that the baby's official name is simply X.