Queen Elizabeth II has a 'prickly' relationship with one of her heirs

Queen Elizabeth II has a "prickly" relationship with one of her heirs.

The longest-running British monarch, who has been ruling the United Kingdom for over 65 years now, is preparing both Prince Charles and Prince William to inherit her crown, but it's William that she's more focused on.

SEE ALSO: Could Prince William pass over his father Prince Charles to inherit the crown?

Though Charles is first-in-line for the throne, he hasn't always had the best relationship with his mother.

"It's no secret that [Elizabeth] and Charles have had a prickly relationship at times," historian Robert Lacey noted to People. "There has always been a special closeness between William and the Queen, and she has taken a particular interest in him."

So much so, that Her Majesty has been focusing her attention on training William to be king since his adolescence.

"When William became a teenager, she would have him at Windsor Castle and would open the state boxes and guide him through the papers," Lacey said. "It was William's constitutional education."

Though Queen Elizabeth may favor William over Charles, that doesn't mean that she would be able to award him the crown over his father. Rumors have swirled for months that the move could happen, but according to the 1701 Act of Settlement, the queen has no such power.

The act requires that the current monarch's heir to the throne must be his or her direct successor, meaning Charles will be king barring an unforeseen tragedy.

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