Article continues below advertisementThough King Charles and Prince Harry's icy relationship thawed out after their recent reunion in London, an insider claimed there's a slim chance the Duke of Sussex will ever rejoin the British monarchy.The father-son duo had a private meeting for around an hour on Monday, September 10, at Charles' home, when Harry was in town for work and charity events.Article continues below advertisementPrince Harry Can't Be a 'Half-In, Half-Out Royal'Source: megaKing Charles will maintain Queen Elizabeth II's rule that no one can be a 'half-in, half-out' royal.