Trump chose Todd Ricketts, an outspoken opponent of Trump's presidential bid, as his deputy commerce secretary.
Ricketts backed Wisconsin Gov. Scott Walker early in the GOP presidential primaries; his brother Pete Ricketts, the Republican governor of Nebraska, supported Trump after he became the presumptive nominee in May.
At a rally in Nebraska that month, Trump took a jab at Todd Ricketts.
"I love Pete, but I think his brother doesn't like me as much as he does," Trump said. "I like him so much, I'm starting to like the Chicago Cubs again." The Ricketts family has owned a controlling stake in the Cubs since 2009.
Announcing Todd Ricketts' selection this morning, Trump called him "an immensely successful businessman with unparalleled knowledge of the finance industry."
Trump went on to praise the work that the Ricketts family has done with the Cubs, the reigning World Series champions, even though he previously criticized their handling of the storied franchise.
In the announcement, Trump said, "The incredible job he and the Ricketts family did in the purchase and turnaround of the Chicago Cubs - one perfect step after another, leading to the world championship - is what I want representing our people."
But he didn't always felt that way. During the campaign, when some members of the Ricketts family were funding super PACs that spent millions of dollars against Trump, he fired back. In February, Trump tweeted that the family was "secretly spending $'s against me. They better be careful, they have a lot to hide!"
When asked what he meant by that during a meeting with The Washington Post's editorial board in March, Trump said, "It means that I'll start spending on them. I'll start taking ads telling them all what a rotten job they're doing with the Chicago Cubs."
Family TiesTodd Ricketts comes from a wealthy politically active family with deep connections.
His father, Joe Ricketts, is the billionaire founder and a former CEO of online brokerage TD Ameritrade, and he founded the digital news site DNAinfo in 2009.
Todd Ricketts' brother Tom Ricketts is the chairman of the Cubs, and Todd Ricketts, Pete Ricketts and their sister, Laura Ricketts, are members of the team's board.
Pete Ricketts is in his first term as the governor of Nebraska.
Laura Ricketts' political ties differ from the rest of her family's. She held fundraisers for Hillary Clinton during this election cycle and made multiple donations to her campaign. Laura Ricketts, who is a lesbian, was inducted into the Chicago Gay and Lesbian Hall of Fame and is the first openly gay co-owner of a major sports franchise in the United States.
Political PlaysAt several points during the presidential campaign, Todd Ricketts and his parents were active in trying to stop Trump from becoming president.
Todd Ricketts was a finance co-chairman for Walker's failed presidential bid. After Walker dropped out, Ricketts reportedly got involved with the anti-Trump Our Principles PAC, which released ads against Trump.
Federal Election Commission filings show that matriarch Marlene Ricketts made $4 million in donations to Our Principles PAC in January and February. Joe Ricketts gave the group $1 million one week after Trump's tweet about the family. Marlene Ricketts gave the group an additional $500,000 in March.
Joe and Marlene Ricketts also gave millions of dollars to Future45, an anti-Clinton PAC that they largely bankrolled along with casino magnate Sheldon Adelson.
Tom Ricketts was asked about Trump's tweet during a news conference relating to the Cubs.
"It's a little surreal when Donald Trump threatens your mom," Ricketts said, according to CSN Chicago, an NBC affiliate.
"The fact is, whether it's my mom or my dad on his Ending Spending stuff or my sister on marriage equality or my brothers and what they do or what we do with the team, we're pretty much an open book," he added.
Ending Spending is a group founded by Joe Ricketts that says its purpose is ending wasteful government spending. Todd Ricketts is listed as the director and CEO of Ending Spending on the group's website.
"We stand up for what we believe in. We support the causes that we think are important. That's what America should be. That's who we are," the site says.