You would look at the picture above and think "What in the world could they have in common?". But beyond the technicalities of genre, musical style, both bands (and many more) share a story of friends.
Dream Theater's story began in 1985, when they started out under the name 'Majesty' with the core of the group formed by guitarist John Petrucci, bassist John Myung and drummer Mike Portnoy. A series of line-up changes followed with vocalist James LaBrie entering in 1991 and keyboardist Jordan Rudess in 1999. And that is how the amazingly technically proficient progressive-metal band is identified around the world. The former three in particular shared the closest friendship having known each other since college. And interestingly enough, they have married three members of a single now-defunct female metal band.
Backstreet Boys were formed under a fledgling entrepreneur in 1993. AJ Mclean, Howie Dorough and Nick Carter knew each other from numerous auditions in Orlando. They later met Kevin Richardson who was brought in by their manager. Kevin in turn also suggested and brought in his cousin Brian Littrell. With three members in their late teens, one barely out of his teens, and one barely into his, they literally grew up on stage. They became friends along the way to their meteoric rise as one of the biggest pop acts in history, and now (sans the old hysteria) also on their way to becoming the most enduring.
The real parallel that I am trying to draw comes with a truly 'dramatic turn of events' that happened for both bands. In June 2006, Kevin announced that he will be leaving the BSB. He no longer felt that his heart was in the non-stop touring and the current scenario of the music industry. He went back to start a family, and work on a career as a stage and film actor. For similar reasons of exhaustion from touring, in 2010, Portnoy suggested to his DT band-mates to take a five-year hiatus. The others obviously did not agree, and after supposedly a long deliberation, Portnoy decided to leave the band in September 2010.
The narrative differs a bit though. Kevin's departure was perfectly amicable. The rest of the boys never even thought about a replacement. Musically speaking, Kevin formed the baritone in their five-part harmony which is since missing. In most choruses though, Kevin would scale down to bass, so the difference is not noticeable since AJ or Nick can cover those parts. Most of his singing parts are covered by Howie. In terms of group dynamics, Kevin was the leader (being the oldest member). Brian owes him his entry into the group. Nick and AJ mention him as a big support in their battle to overcome substance abuse. On the DT front, nobody would have imagined that Portnoy would leave the group, being one of the three founding members. With the complex musical style that they have, DT could not afford having a temporary drummer. So, they selected Mike Mangini as a replacement. Meanwhile, Portnoy recorded drums for Avenged Sevenfold's album in place of their late drummer. He was expected to join the group but the band decided against it. Portnoy attempted to reconcile with his old friends, but they had moved on beyond repair.
As it stands now, Kevin is making his mark gradually as an actor, winning awards and receiving good critical reviews for his role in the independent film 'The Casserole Club'. Over the past five years, he has made appearances and performed with the BSB. Though unlikely to happen, the rest of the boys often mention that the door is always open for him to return. DT are due to release a new album this fall. Portnoy is working on a new project himself and his new band will also be recording an album.
Being a fan of both these bands, it was interesting for me to note these parallel events. Though I became a fan of DT much after their initial changes, I can safely assume Portnoy's departure was truly the most impactful event. I have been a fan of BSB for nearly half my life, and have always known the group as a quintet. It does seem unlikely that Kevin will ever return, but probably more likely than Portnoy returning to DT. Still, a more realistic possibility would be that Kevin at least returns just for a 20th anniversary concert/tour, which I will be eagerly waiting for in 2013.