Epic Riff: Five "oh"s, to two different rhythmsnote "You Got It (The Right Stuff)" and "Hangin' Tough", are two of the most iconic vocal riffs in pop music.
Face of the Band: As noted in that trope page, Boy Bands tend to avert this. That said, Donnie tends to be the most out-in-front in terms of on-stage banter and crowd interaction.
Growing the Beard: The group's evolution from their debut through Step By Step (coupled with some literal beard-growing), as well as their more modern sound on The Block and 10.
Harsher in Hindsight: Jon leaving the group was the final straw that led to their breakup. Years later, Jon revealed on Oprah that he suffered from panic attacks pretty much the entire time he was in the group, and that by the time he quit, they had gotten so bad that he could barely function in everyday life, much less on stage. Jordan was in the same episode with Jon, and revealed that he also suffers panic attacks, but to a much lesser extent. While he's largely been able to keep them in check since they reunited, Jon still struggles with panic issues. During a live, televised performance for iHeartRadio in 2013, Jon couldn't sing his solo part in "Survive You", left the stage, and didn't return for the rest of the show.
When the press said that Jon was dating Tiffany, the fangirls screeched. Several years later Jon and Tiffany said yet again that they only were friends... but why is this different, huh? Because Tiffany added "I and Jon never dated... because Jon is Straight Gay, you know". Guess the fangirls were screwed either way, huh.
In the early-to-mid 2000s, VH1 aired a series called Bands Reunited. The premise is simple enough; they find bands that split up under less than amicable circumstances, hunt down the members, and ask if they would be willing to perform a short concert for charity. They tried this with New Kids, and it ended up being one of the most tense episodes of the series: a couple of the guys said they'd only do it if everybody else agreed to do it, and at least one flat-out refused to even be seen on camera (needless to say, the concert didn't happen and the show was essentially Killed Mid-Episode.) Fast forward a few years, and they did reunite, not just for a one-off, but producing new material, and doing very well at it, to boot.