"I used to ask him questions about everything, and he always told me the funniest things," said Jerron McMillian, a safety for the Green Bay Packers and Belcher's teammate at Maine.
"He laughed a lot," McMillian said, "but he was always serious about his work. He'll play with you, but when it's time to work, he's tuned in, he's focused, and he's really emotional about how he does things."
Only a small percentage of undrafted players make it in the NFL, but Belcher managed to beat the odds. At one point during his initial training camp, Pioli told members of the Chiefs' front office, "I really like this guy. I really think this guy can be a player."
He wound up playing in all 16 games as a rookie, even starting three times at linebacker. He became a full-time starter in 2010, when the Chiefs won a surprising AFC West championship.
His base salary this past season was more than $1.9 million.
"He overcame a lot of things — position changes, small school. He overcame all those things through the force of his indomitable spirit," said Dwayne Wilmot, who coached Belcher at Maine and remained in touch over the years. "He lit up when he spoke about his mom, or hugged his family after games. His love for them fueled him to reach the heights he was able to reach."
Belcher met Perkins through Chiefs running back Jamaal Charles and his wife, Whitney, a cousin of the slain woman. Perkins was active in the Chiefs' women's organization, and the two of them recently had a baby girl.
"I was so excited when he became a father," Wilmot told the AP in a phone interview, "because he would be a great father."
Kansas City police said Belcher and Perkins had been arguing recently, and a friend of the couple, Brianne York, said the root of the argument was that Belcher "sometimes he would just be down in his man cave or whatever," and Perkins wanted to spend more time as a family.
Other friends said Perkins was out late at a concert before their final argument took place.
"It doesn't seem that that would be the end of their story," York said. "It just seems like if things didn't work out, they would have gone their separate ways."
The reality is that nobody may ever know exactly what happened in those final hours, minutes, seconds.
"I think what we try to do is explain the unexplainable," said Chiefs linebacker Andy Studebaker, who was close to Perkins as well. "This is such an unexplainable event that I don't think we could easily get through it with a single-sentence explanation."
Unexplainable, and with devastated families left behind.
"I was once told the hardest thing a person can go through is burying their child, so my heart goes out to their families — Kasandra's and Jovan's families," Johnson said. "You can just imagine what they're going through right now, and as a team, we lost a brother. It's going to take time, but life goes on."
Associated Press Writers Heather Hollingsworth and Nancy Armour contributed to this report.