I keep killing the battery on my 3DS from marathon sessions of Fire Emblem: Awakening, so I guess it's safe to say I'm hooked.
I think I've talked about this before, but generally when games give you a myriad of characters to recruit over the course of the game, I tend to get super attached to whoever the first people are to fill up my party. By the time some new stranger comes along, not only have I been leveling my original party, but I've gotten to know them. So I treat the new people with a cold shoulder, because they're new and strange and not part of the "in" crowd.
So you can imagine in a game like Fire Emblem, that has nearly 50 characters to recruit might pose a bit of a problem for me. And it's true... it is very easy to become heavily reliant on a specific group of characters. Frederick is a problem especially, because he begins the game as an advanced class and can feel overpowered. I ended up pairing him (and marrying him) with Sumia, and the speed bonus she gives him let him start attacking twice in a turn very early on, turning him into even more of a beast.
However if you don't branch out, you're really missing out on a lot the game has to offer, both in terms of different classes, and more importantly, the amazing interactions between all the characters. Every character in Fire Emblem has an interesting personality with a lot to say, and even more interesting support interactions with the other people in your roster.
Once I started to realize how rich the interpersonal tapestry of the game was, it actually made the permadeath system a little easier to cope with. Sure, if someone you've grown attached to (or someone that's really high level) dies, it totally sucks. But on the other hand, it opens up an opportunity to begin using one of these other characters more frequently.
You just don't want to end up losing a level fifteen guy, and having to replace him with a level three guy because you didn't keep up the training and spread around the experience evenly.