Harrison and Venus, who is from New Zealand, beat Donald Young of the U.S. and Santiago Gonzalez of Mexico 7-6 (5), 6-7 (4), 6-3 on Saturday to earn their first Grand Slam title.
Venus moved to the United States when he was young and he and Harrison, who was born in Louisiana and now is based in Texas, grew up playing tennis together. They were coached by Harrison's father, Pat, who is still Venus' coach.
"It's even more special that we're able to do it alongside each other, because he's like a brother," the 25-year-old Ryan Harrison said. "He's been a part of my family. We have been a home away from home for him ... He was like a brother growing up. He taught me how to drive, taught me how to do a lot of things. Didn't teach me how to talk to girls, one thing he didn't teach me how to do.
"But it was special, because, you know, he was someone who was there for a lot of memorable moments of my life, including my wedding, being one of my groomsman. To have him with me and the most special moment of my career is surreal."
The 27-year-old Young, who was born in Illinois and is now based in Georgia, was trying to win his first tour-level title in singles or doubles.
Harrison and the 29-year-old Venus had only played four tournaments together coming into Roland Garros, winning a title at Estoril last month — but falling in the opening round at each of the other three.
"Two-and-a-half, three months ago, (Venus) decided that he was going to be looking for a partner for the clay season, and I didn't have anybody," Harrison said. "We both were very excited. It just kind of all came into play.
"We haven't talked about (Wimbledon) yet. I don't think we wanted to get too far ahead of ourselves. Because as you're in the middle of the week, there is a certain level of jinx you don't want to put on yourself ... I think the logical thing would be to play it out for the rest of the year."
Harrison, who reached a career high of No. 42 in the singles rankings in May, hopes the doubles title will serve as a springboard.
"Obviously I'm a singles first player," he said. "A lot of times, in my opinion, you see guys who have really great singles ability actually have big doubles results first because it's a little easier at times to waive the nerves of the big moments and big stages.
"This is super special. Wouldn't have been more happy to do this with Michael and do it this summer. But I'm hoping this can lead into singles success as well, and I know my confidence will be very high coming off of this."
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