Elon Musk brought an important guest to the Army-Navy Game Saturday … his 3-year-old son … and there’s backstory here.

X Æ A-Xii was perched on his dad’s shoulders as they watched Army beat its rival by a 17-11 margin.

Elon and son stood out … they were in civilian duds and surrounded by uniformed fans.

The two were all smiles as they posed with the Army Mules mascot at Gillette Stadium in Massachusetts.

Elon was rooting for the winning team … he’s an Army fan.

As for the backstory … Elon and Grimes are in a custody fight over their 3 kids. She filed for parental rights back in October.

BTW … another Elon development — he restored Alex Jones‘ X account, this after users voted to bring him back to the platform. There were nearly 2 million votes, and 70% gave Jones — who, among other things, denied the Sandy Hook massacre was real — a thumbs up.