Athena said:Robin is the playable avatar from the newest installment of the FE series. He/She (you can pick gender along with name and customizing physical attributes when starting the game) is a main character in the game and functions something like a PC, since he/she is effectively designed by the player. Robin is available from the very beginning, is not allowed to die, and plays a crucial role in the game's plot, despite not being a Lord (Lord being the typical class for the main character of an FE game; in this case, Chrom and Lucina are both Lords with Chrom being the main Lord). Robin is also unique in the sense that he/she starts out being able to use both Magic and Swords; traditionally in FE characters are either fighters or mages and very rarely do they mix (though some later available prestige classes do offer the availability to use magic and a weapons as well). The aspect Robin mentions about tomes being used up references in-game mechanics in FE; almost all weapons and magic tomes in various FE games have a certain amount of uses before they break, with weaker things having more uses and some powerful ones only allowed to be used maybe 5-10 times.
Lucina is another character from FE:A. She is a secondary Lord who appears early in the game but does not actually become playable until later. She initially appears as a masked fighter and takes the name of Marth, only to later be unmasked as a woman with her identity revealed (though there's more to her identity than just her gender and name, I won't spoil it here since it's plot-relevant). Because of her connection to Marth, I originally thought that she might replace Marth as an available character in SSB, or appear as a different skin for him; they're also both fast characters with smaller builds. I would be disappointed but not surprised if she ends up being simply a Marth clone, though I do hope that there will be something that distinguishes them.
Chrom, despite being the main character of FE:A seems to only be in the game in Robin's final smash.
Wait...so if Chrom is part of Robin's final smash that means that if I use female Robin and access her final smash my OTP can battle together!! Also for you non FE players you can marry your characters in game (well some characters can't marry certain other characters), and in my run with the female Robin I had her marry Chrom, they're love story is so cute and kinda kinky. Anyways I like how they sort of acknowledged the fans shipping of Robin and Chrom.