For fans of “Hawaii Five-0,” this weekend marks two reasons to celebrate. Aug. 23 is series star Scott Caan’s birthday and Aug. 24 is series lead Alex O’Loughlin’s birthday. Both actors are top favorites among the “H50” fandom and all weekend fans have taken to social media to wish the two actors well and continue obsessing about the well-anticipated start of season ten.

Beyond wishing the two actors a happy birthday, fans also use the dates to sing not only their individual praises but to also applaud the two actors as a duo. Fans call the two “McDanno” and in some parts of the fandom, “ship” the two characters as a virtual couple. From the start of the series McGarrett, played by O’Loughlin, and Danno, played by Caan, have had what was once called a bromance — a deep friendship between two men — which has now morphed into more-than-brothers-better-than-besties kind of relationship.

MCDANNO POWER

McDanno fans are tried and true, and always the two actors’ birthdays seem to remind fans about how much they really love when O’Loughlin and Caan work together in an episode. The more popular episodes tend to be the ones that feature McGarrett and Danno side by side on a case, mostly driving each other nuts, but also enjoying hanging out together and always concerned about each other’s safety and psyche.

So it is no secret that the most popular episodes of every season are the ones in which McGarrett and Danno lead the case of the week and when the storyline focuses on the two partners. Fans crow the loudest when Caan is not featured in an episode, and based on his shooting schedule, he tends to be “in New Jersey” every three or four episodes.

While fans fuss about his lack of screen time when he is in an episode, their love for his return is always powerful enough to drive up ratings for an episode featuring McDanno. The highest-rated episode of season nine was “Ka hauli o ka mea hewa ‘ole, he nalowale koke” (“A bruise inflicted on an innocent person vanishes quickly”) which focused on McGarrett trying to find out who put Danno’s daughter Grace (Teilor Grubbs) in critical condition after she and a friend are involved in a car accident. The episode showed how much McGarrett would do anything for his friend but also his love for Grace and Danny’s family.

MORE THAN JUST FRIENDS

Fans also have a lot to say when McGarrett is not featured in an episode, but he is pretty much a constant in most episodes. Still, it is the McDanno duo that most fans seem to love best. While their infamous “carguments” have lessened over the years, it is still poignant when they talk to each other about family matters, feelings about the team, and all manner of deep issues while McGarrett drives Danno’s car, or at Five-0 headquarters.

These are the scenes that matter the most to McDanno fans — when the two friends seem to be there for each other and support each other on every level. Over the last nine seasons, Danny has saved McGarrett’s on countless occasions — he’s rescued him from Wo Fat, the Taliban, and a sensory deprivation chamber; he’s given McGarrett part of his liver; supported him through radiation poisoning; and helped him find justice for the death of his father John (William Sadler) and his surrogate father and friend, Joe White (Terry O’Quinn).

McGarrett has also been there for Danny and his children — rescuing Grace after she was kidnapped; helping Danny avenge his brother Matt’s death; saving him from a Colombian prison when he was illegally extradited; saving his life when he was poisoned, shot, and even when he found out Grace’s half-brother Charlie (Zach Sulzbach) was actually his own child. Really they have been there for each other for more than a lifetime of love and friendship. They are two friends who have more than one reason to call each other family.

OFF-SCREEN LOVE AND ALOHA

This weekend fans are busy signing online cards and donating to their favorite charities and causes in honor of their birthdays. Caan is a long-time supporter of the charity A Walk on Water which provides surf therapy to children with special needs and disabilities. Caan is often seen surfing with kids at some of their events and also is an ambassador for the group. He has also worked with Surfers Healing, Thera Surf, and Life Rolls On.

O’Loughlin has been a long-time supporter of organ donation so many fans give to causes like Taylor’s Gift, which O’Loughlin has supported in the past, and the Hawaii counterpart of Donate Life — Legacy of Life Hawaii. Alex O’Loughlin Fans for Organ Donation, a fan group, are celebrating both his birthday, as well as the 50th anniversary of the first organ transplantation in Hawaii, with their 2019 Alex O’Loughlin birthday campaign for legacyoflifehawaii.org.

One of the most memorable McDanno episodes has to be when Danno gave McGarrett part of his liver in order to save his life in the season six finale. Fans often mention this connection to a cause that is dear to O’Loughlin’s heart.

Wendie Burbridge writes the “Five-0 Redux” and “Magnum Reloaded” blogs for staradvertiser.com. Follow her on Twitter and Instagram.