Too many likable characters in that franchise. Damn. Let's see. Using only American releases:
Fire Emblem Rekka no Ken
Hector, Lyn, Rebecca, Lilina, Nino, Lloyd, Sonia, Nergal, Jaffar
Hector is a boss. I don't need to discuss how he powerpwns everything in his way, has the best story arcs, has blue fricken hair, and absolutely destroys Girlwood as a Lord.
Lyn is a boss too. And I know I said "Girlwood" to refer to Eliwood, but Lyn is a boy in a girly way; she is speedy and mmm qimme dat. Also, Blade Lord has some of the best animation in the GBA games.
Rebecca is my go-to Archer. I know she isn't optimal especially for HHM 5Star runs, but if training can happen then you can be sure I'll be training her.
Lilina despite only being in the game for the end scenes has gotten my attention admittedly from FE6...but even so she's cute.
Nino, like Rebecca, is not optimal. And she is HARD to train. But boy, if you manage to train her then she will come out boss. Best Sage in the game by far. Qimme those growth rates!
Lloyd had one of the most believable crises for a villain. Having to kill his own "sister" due to some tricked loyalty to a bad gang, his father and brother being killed by Nergal...man I love this guy.
Sonia is a huge biatch and I love her for that. Even though I tend to denounce those kinds of villains, Sonia did it pretty damn well and even had the stats for it!
Nergal killed Ninian. Boss mode x 999!
Jaffar...x Nino forever.
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Fire Emblem Sacred Stones
Eirika, Ephraim, Seth, Tana, Neimi, Colm, Syrene...there are more but I can't be bothered to boot the game up. Anyway I love them all because mmm qimme dat, and Eirika, Ephraim, Tana, and Colm all happen to have blue hair which automatically makes them important and/or awesome. ;p
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Fire Emblem Path of Radiance/Radiant Dawn
Ike? I guess. Didn't really gravitate towards the characters in these installments. Kind of just blew through the game and said "is that it?" ;p
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Fire Emblem Awakening
Chrom, Lucina, The Vaike, Lissa, Owain, FeMorgan, FeAvatar, Male_Grima, Severa, Philander (Inigo), Olivia, sheesh there are too many characters. ;p
Love them way too much. They have THE BEST personalities. Especially "I do not 'imply'."