So eagerly did Joe Biden embrace his attack-dog role as Barack Obama’s running mate in the 2008 presidential campaign against Sen. John McCain that some observers at the time thought a cross-aisle friendship might end.

Biden (pictured above, in an emotional moment on Thursday), then a Democratic senator from Delaware, repeatedly tied the GOP senator from Arizona to unpopular outgoing Republican President George W. Bush. That was an inevitable strategy; but Biden went personal, calling McCain an “angry man” while campaigning in Florida and challenging the war hero’s manhood for hiding behind attack ads against Obama.

“In my neighborhood where I came from, if you got something to say to a man, look him in the eye and say it,” Biden declared at one point.

New York University professor Paul Light told Reuters at the time that the Biden-McCain friendship might be irrevocably broken.

“John McCain is not going to forgive. He’s not a forgiving type,” he said.

All that is water under the bridge, of course. It did not take long for the two men to resume their friendship, to which Biden paid touching tribute on Thursday at the late senator’s memorial service in his adopted home state of Arizona.

“My name is Joe Biden. I’m a Democrat,” Biden said, pausing to acknowledge the laughter and applause inside the North Phoenix Baptist Church. “But I love John McCain.”

An uncharacteristically somber Biden gave only the slightest hint of the acrimony from that 2008 campaign.

“I always thought of John as a brother,” he said, dabbing his forehead with a white handkerchief. “We had a hell of a lot of family fights.”

Many political friendships are phony constructs, pleasantries on the Senate floor preceding blistering attacks, or throwaway lines uttered at banquets and campaign podiums. By all accounts, the Biden-McCain friendship was real.

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Biden recounted first meeting McCain. Biden recently had been elected — at age 29 — and was serving on the Senate Foreign Relations Committee. McCain, a former prisoner of war, was working as a Navy liaison officer, accompanying senators on trips abroad.

“I always thought of John as a brother. We had a hell of a lot of family fights.”

“For some reason, we hit it off from the beginning,” Biden said. “We were both full of dreams and ambitions, an overwhelming desire to make the time we had there worthwhile, to try to do the right thing, to think about how we could make things better for the country we loved so much.”

McCain died Saturday from the same form of cancer that claimed the life of Biden’s son, Beau, in 2015. That death played a decisive role in Biden’s decision not to run for a third time for the presidency in 2016.

Biden praised McCain’s legacy and his devotion to respect, decency, honor, and basic fairness.

“John’s code was ageless, is ageless,” said Biden, later adding, “John’s story is the American story. That’s not hyperbole.”

“Even though John is no longer with us, he left us pretty clear instructions.”

Biden said his friend “could not stand the abuse of power, wherever he saw it, in whatever form, in whatever country.”

The former vice president said he and McCain both lamented the increasingly nasty, partisan tenor of the country and the Senate. He said he and McCain came in for criticism by their caucus leaders in 1996 for sitting next to each other too frequently in the Senate chamber during debates.

“That’s when things began to change for the worse in America, in the Senate … All we do today is attack oppositions of both parties, their motives, not the substance of their argument,” he said.

Related: The Good, the Bad and the Ugly of John McCain

Biden, whose personal losses include not only Beau but his first wife and a daughter in a traffic accident shortly after his first election, offered firsthand experience in dealing with personal tragedy. He warned McCain’s relatives that they will deal with flashes of pain long after the world expects them to have gotten over it.

“You’re gonna feel like you did the day you got the news. But you know you’re gonna make it,” he said. “When the image of your dad, your husband, your friend, crosses your mind, and a smile comes to your lips before a tear to your eye, that’s when you know. And I promise you. I give you my word. I promise. I promise you. This, I know. That day will come. That day will come.”

As for all other Americans, Biden urged his fellow citizens to honor McCain by the way they live.

“John believed in us. I think he believed in the American people, not just all the preambles, the Constitution,” he said. “He believed in the American people, all 325 million of us. Even though John is no longer with us, he left us pretty clear instructions.”

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