Grimes is suing Elon Musk and asking for physical custody of the three children they share, according to court records obtained by Insider.
The parental rights lawsuit was filed on September 29 in the San Francisco Superior Court. The lawsuit was first reported by The San Francisco Standard, but the details of the petition were previously unknown. The two are not married.
Grimes, whose legal name is Claire Boucher, is seeking physical custody of her and Musk's kids — 3-year-old X and 1-year-olds Exa and Tau — as well as joint legal custody.
Her lawsuit comes about three weeks after Musk quietly sued her, seeking to "establish the parent-child relationship" between him and the three children. Grimes' lawsuit also requests that Musk's suit be thrown out.
Her petition includes a "standard restraining order" that would prevent the children from being moved out of California by both her and Musk without the explicit written permission of all parties or a court order. Such restraining orders are standard in most custody cases in California, according to Neama Rahmani, a Los Angeles-based attorney and president of West Coast Trial Lawyers.
Grimes also asked the judge to mandate that Musk pay her legal bills in the suit, as well as the cost of hiring experts or a court-appointed legal guardian as part of her legal action.
Lawyers for Grimes and Musk declined to provide comment on the lawsuits when reached by Insider. Musk did not respond to efforts to reach him.
Grimes' decision to seek joint legal custody with Musk and primary physical custody for herself is common among parents who are no longer together, according to high-net-worth family law attorney Holly Davis of Kirker Davis. The practice is especially common when the two adults live in different places, such as Grimes and Musk, who reside in California and Texas respectively.
"If that's what Grimes is wanting, it would be really helpful for her to be able to show that that's what she already had in their agreement," Davis told Insider.
Differentiating legal custody and physical custody allows parents to share decision-making and rights of access to the kids without an equal custody split, Davis said. One parent is typically deemed the primary parent and has custody of the children more days out of the year. The primary parent also usually receives child support.
The secondary parent has custody of the child in accordance with a possession schedule implemented by the court. Many modern-day possession schedules offer a 45-55 split between the parents, Davis said.
The lawsuits are the latest in Musk and Grimes' rocky relationship
While it had been previously known that Musk and Grimes had two children, last month it was revealed that the billionaire had fathered his third child, Tau, with the musician via surrogate in 2022.
The couple's eldest son, commonly called baby X, has become something of a public figure in recent years. Musk has been spotted on several occasions bringing the three-year-old along with him to meet international leaders, sit in on meetings at his companies, and to SpaceX rocket launches. The child became such a common sight at X, formerly known as Twitter, that he even got his own badge last year.
Last month, Musk posted on his social media site X that his son was his "emotional support human" after bringing the child along to a meeting with the president of Turkey in New York. When Turkish president Recep Tayyip Erdoğan asked where his wife was, Musk replied, "We're separated, I take care of him mostly."
Grimes has previously said she'd prefer to keep her children out of the public eye. "Whatever is going on with family stuff, I just feel like kids need to stay out of it, and X is just out there," she told Vanity Fair last year.
The lawsuits are just the latest sign of cracks in the relationship between Grimes and Musk. The couple has been off-and-on again since they first started dating in 2018 and later broke up for the first time in 2021. At the time, Musk said the issue came down to his work in Texas and Grimes' career in Los Angeles making it too difficult to stay together.
The conflict appeared to come to a head last month when Grimes wrote and then quickly deleted a September 7 post on X calling for Musk to "let me see my son or plz respond to my lawyer."
In the post, Grimes also expressed ire over Musk's relationship with Shivon Zilis, an executive at his startup Neuralink, who he fathered a set of twins with in 2021. Musk has 10 known children.
"I have never been allowed to see a photo of these children until this moment, despite the situation utterly ripping my family apart," she wrote in a response to a photo of Zilis, Musk, and their two children.
Walter Isaacson wrote in his biography on Musk, which was released in September, that Grimes didn't learn Musk had fathered twins with Zilis until it was first revealed by Insider last year. The biographer said Zilis and Grimes were friends at one point and were even unknowingly in the same hospital at the same time due to their pregnancies.
Grimes and Zilis later posted on social media in September to say they were no longer feuding. Musk notably did not respond to Grimes on social media.
