I'm not sure if this has been posted about here, but there's a cool Easter Egg in FE Echoes.
If you leave Kliff and Faye behind with Alm, but head back to Ram Village with Celica before going to Zofia Castle, you can actually recruit Kliff and Faye with Celica. They even have special dialogue with Celica for their recruitment conversation.
It's obviously not practical to do this, as Alm needs them more and you would have to go out of your way to grind them up to par in the Thieves Shrine if they are to be at all useful for Celica. But it's a nice attention to detail nonetheless and could be fun to mess with on repeat playthroughs. I also know that Faye offers a support bonus to Celica, and Kliff probably does too (I haven't put them together to see yet). If you are willing to train them up, both of them can make for good Cavaliers since Celica only gets one in the late game, and Faye could also be a Pegasus Knight which can be useful for those desert and swamp maps.
Unfortunately, this can't be done with Silque, Python, and Forsyth, at least from what I've heard, and of course, Alm doesn't get access to any of Celica's route until post-game.