Leif
Oh Leif... Leif is actually a playable character in Genealogy, the game before this one, and there he was just Seliph's cousin who was desperately trying to fight off the Empire before we could reach him. Well... this game shows us exactly what he was going through at that time! In fact, one of the chapters in Thracia 776 happens right when Seliph joins up with Leif.
As a unit, Leif is... interesting... his bases are trash. Most of them aren't even above 5. That and his team consists of a bunch of dudes who KNOW how to survive one round of battle. But is he a bad unit? Far from it! First of all, there is a point in the game where you lose all your units but Leif, and since he'll be the only guy who transfers, he'll prove very useful, and with this knowledge, you'll be pouring a lot of stat boosters into him. That and he has a 1-2 range sword that he can use to fully heal himself anytime. That's amazing! But wait, it doesn't stop there. Leif also provides support bonuses for a ton of units in the army and can singlehandedly make the difference between hitting or not hitting, in a game where hitrates are calculated with 1-rn. You can also give him the King Sword to increase this ability, making Leif one of the most useful units in the game. That and after a while, his combat won't be too shabby thanks to the fact that enemies in this game suck, and are also easy to double (a ton of enemies have 0 speed, if Lilina was in this game she'd easily prey on everything). My Leif was particularly amazing, he got most stats capped by the end of the game, althougb I was just lucky. Oh yeah, he also had 11 move. 11 move. Let that sink in.
I also like Leif as a character. Although he had an established personality in Genealogy of the Holy War already, this game expands Leif beyond that. To contrast Roy, the idealistic pup who's kinda boring, Leif is an impulsive and often immature brat who cares too much about people to make rational choices. This actually gives him a lot of room to grow and develop some character, something Roy dearly lacked. The reason I am comparing him to Roy specifically is because like Roy, Leif also has an advisor who always comments on the unfolding events and provides him with helpful counsel. Unlike Roy, however, Leif needs the help of this advisor, Augustus. Augustus is actually a voice of reason in Leif's conscience and knows that Leif's behavior can lead to tragedy, and knows that he has to stand up to his decisions to save him from himself. Whereas Roy is always right and it makes Merlinus, his own advisor, look like an idiot and an asshole. Funny. Leif improves the performance of his allies both in gameplay and story. Anyway, Leif is just a top-tier lord. Now my fourth favorite.
Finn
Finn! Yes, ladies and gentlemen, it's Finn! Again! He appears in the first generation of Genealogy, the second Gen (and is the only character to do so) and if that wasn't enough, also THIS game. Quite literally a life-long sworn knight of the realm.
Finn is godly in this game. He comes with the Brave Lance. IN CHAPTER 1. The brave lance is perhaps one of the most powerful weapons in the series, especially the Thracia 776 incarnation, and only HE can use this one! That and his bases are amazing for the beginning of the game despite not being promoted, and to top it all off, he's a cavalier, meaning he has Canto! Oh yeah, may I mention that he can also one-shot armies of horses with the horseslayer if you give him that? Yeah.
I may have talked about Finn as a character already, but I'll do it again anyway. Finn is a devoted knight to his liege, like many in the series. But the reason why he stands out so much among them is because of what lengths he is willing to go through, and the fact that he actually goes through them. Finn first appears in the Prologue of Genealogy, as a knight accompanying Cuan, the prince of Leonster. He takes Sigurd's campaign as an opportunity to train and become an asset to his liege. After Gen 1, almost everyone dies, including Cuan, but Finn is one of the survivors (since he wasn't even at the scene) and is seen alive and well in Gen 2, where now he is helping Cuan's son, Leif, fight off the Empire. The fact that he appears there at all is cool in on itself, but then Thracia 776 comes in and actually tells you all Finn has done. After Cuan's death, Leonster was burned to the ground. Finn had to carry an infant Leif out of there and seek refuge in a nearby village, all the while fending off any assailant trying to catch up. When he arrives at Tahra, he has to keep Leif in hiding, and starve himself for Leif to grow up. Oh and did I mention Finn also has a daughter that he must also raise alongside him? Yes. He does. Years go by and it seems like everything is ok, but nope, this is right in Wyvern territory, so he hightails all the way back to a remote village to the coast, Fiana, where the locals greet him, broken, and half-dead. After that, it was finally peace for some time... Leif and Nanna were being taken care of, and Finn could finally rest. AFTER THAT he participates in Leif's war against the Empire and joins with Sigurd's son once and for all to end all chaos on Jugdral. This has got to be one of the best character arcs in the entire series. Finn deserves every single bit of respect that is being attributed to Leif and I am proud of this man. FE4 also has a manga btw, which explores the depths of many characters, like Finn, and it actually details his relationship with Lachesis, and pretty much how he came to be a dad.
Nanna
Speaking of which, here is Nanna, Finn's little girl! She was actually also playable in Genealogy, in Gen 2, and the daughter of Lachesis (and as established as canon thanks to this game, Finn's as well). She was actually one of my best units there, and here is no different. Nanna comes with her Earth Sword, which she also has in Genealogy (provided her mom got it in Gen 1). It's a powerful 1-2 range sword that drains the HP of the target, meaning that Nanna can effectively tank against anytime that doesn't one-shot her. That and she has a horse and can also heal people, being a Troubadour.
Nanna doesn't have a super interesting character arc, she's just this kind girl who hangs out with the main character and has known him for a long time. She does however possess a regal air about her and as the princess of Nordion, she also has connections with some pretty prominent powers in the continent. She's just pretty sweet all around, though, so you can't go wrong with her in your company.
Osian
The first in this list of the people who weren't in FE4. Osian is one of two fighters you get in Chapter 1. He has the Wrath skill. That doesn't like too noteworthy but guess what? In this game, Wrath lets you automatically get a crit when an enemy attacks you on enemy phase. For that reason, he is incredibly easy to train, although you don't wanna expose him too much. He also gets his own personal axe in Chapter 1, The Pugi (sadly I learned of that fact AFTER I was well into the game already), which is an amazing 1-2 axe that even has crit normally. Other than that, he's just a really decent combat unit.
Osian is this kind of guy who is, like Leif, pretty damn impulsive, but in a violent way. Getting on his nerves is a terrible idea, but he's also got a gentle heart. You want him to help you do something? You'll find no better guy. His relationship with Tanya (a character I didn't really train) is also pretty funny, and also kinda cute. (They do hit it off in the epilogue, so all's well that ends well)
Dagdar
This man is a legend, a beast. A prepromoted Warrior that joins in chapter 1, Dagdar is tremendously powerful and even has the accost skill, which lets him easily capture any unit (although the skill becomes a liability anywhere else). For that reason, Dagdar is a valuable asset to your team, as he can easily provide you with the enemy's weapons and inventories, and he has a lot of Con to do it reliably. His growth rates suck, but his bases last him for essentially the entire game, although later on Dark Mages will be his mortal enemies, since because of accost, they tend to attack him twice regardless of if he can retaliate or not, and they can often kill him in two hits because of his low magic, so be very, very careful with him. Unfortunately, I lost him at the final chapter, because he was berserked and he went for one of my own units, who was able to survive the attack, but ended up accidentally killing him instead, and I was too far into the chapter to start over. Sorry bro.
Dagdar is Tanya's daddy, and you can see that she respects him. The guy also has a piece of land for himself up in the mountain, in fact he's the leader of the bandits there, but he keeps them in check! Everything goes to shit when he leaves, but the dude really knows how to manage things in life and seems to have a lot of experience. I like him. He's also got the manly beard. Although he died in my playthrough, we can count of MARTY PARTY to carry on his legacy. I'll make sure he gets out alive next time, tho.
Ronan
I actually used him mainly because a well-known FE Youtuber likes him and made him a meme, but I actually found that I enjoyed using Ronan. He's not a great unit, or anything, but he's got adept, which lets him attack twice in a row occasionally, he has decent movement, and a bunch of action stars, so you'll find that he can casually have another turn more often than anyone else early on. He also has an abnormally high movement growth (yes that's a thing in this game, although 5% isn't all that amazing either way) and he has high magic, so tanking mage is a niche he could potentially work with. Ronan is just a really unique character in a game where personal skills are all over the place as is, and that imo makes him real fun to play.
Ronan is a normal hunter who lives in Ys village (that's what it's called), and just wants to join the army out of sheer will. He is pretty much the incarnation of rebellious youth in this game, pretty much. A decently likable guy all around.
Macha
A myrmidon who joins as soon as the chapter 4 transition begins, and one of those who help Leif break out of his cell to continue his adventure. She has Vantage, which lets her attack before the enemy at all times when she can. She has good speed and not so great strength, but if you do put your mind to training her, she can become a decent unit. She isn't usually all that great but she got really good in my run. She was especially useful to lure enemies and dodge-tank them while everyone else got somewhere safe. She can use axes after promoting so that's cool.
Not too noteworthy of a character, per say, but she isn't a bad one either. She shows appreciation to her comrades in the war and always acknowledges the fact that these people contribute alongside her in the success of the army. She's alright.
I actually think she kinda looks like Trinity from the Matrix, but maybe that's just me.
Lara
Lara is a special case. She starts off as a thief, a class in which she is frankly alright in but she has
ZERO strength, quite literally. You'll have to weapon mages to feed her any kills, although she can still steal things and pick locks, so she isn't a total waste. Where Lara truly shines though is in Chapter 12X onward, because recruiting a certain character with her promotes her into a dancer of all things. And you know how good dances are if you've seen me gush about them long enough.
She is a vivid and youthful girl who is always set on her goals and knows what she wants in life. It also seems like she never forgets what good is done to her so she allows wants to repay the debts she owes, and she's a pretty energetic person.
Fergus
Fergus is arguably one of the best units in the game. A mounted unit who has decent stats all around, but that best thing about him is his FCC of 5. That means that when he doubles, his crit rate is quintupled. If you have 20 crit or more on something, then the second attack is guaranteed to crit. That's pretty amazing.
Fergus is a well-meaning guy, but he's also something of a goof. He's absent-minded and doesn't always think straight before throwing himself into the fray. It also seems like there's more to him than meets the eye, since he can use the Beo Sword, which apparently belongs to Beowulf, one of your units in FE4 Gen 1. I like his air, idk, he gives off chill vibes, but he also seems kinda drunk in his portrait.
Asbel
Asbel is probably the best combat unit you get in this game. He joins with a great tome, Grafcalibur, that has 30 crit on it and 13 might, and he himself has an FCC of 3, so he'll crit very often if he doubles (which he will, he is very fast). After promotion, he can use staves, which is nice, although he won't get much past Heal or Torch staves unless you heavily grind it, but you'd more want him actually fighting.
Asbel has known Leif since childhood. He's in league with Prince Ced of Silesse and has been looking for Leif for three, stopping at nothing to find his friend with whom he always dreamed of liberating Thracia. He also holds great admiration to Ced, who taught him a lot about magic and is fighting despite his own problems. He's a really enthusiastic guy when it comes to his friends, and very loyal.
Pirn
It's creepy that this guy's name is one letter away from Porn Pirn is a good replacement for a thief if they're not that great. Pirn can actually hold his own better than it looks in combat and also do everything a thief can. That and he comes with a high sword rank so even with mediocre strength he can still do good damage if you give him good swords, and can even kill a mage or two in the endgame.
Pirn is an interesting character. He's sort of a Robin Hood character, except he's not really a good person either. He steals honorably and never means any harm, but he also isn't above capturing little girls and making them his slaves (his mansion is full of strippers and female enemies too). He does seem to have friends who trust him and fight alongside him, though, and he is well-respected by those people who willingly work with him. He is a Robin Hood character I actually like, for one.
Linoan
Linoan holds the distinction of being the only character besides Leif to not promote with an item and instead through a specific event, that being visiting a church in chapter 21. She is a cleric who can wield magic and staves, and she is easy to get to A rank staves, so that makes her a really good unit, that and she can pack quite a punch offensively too.
Although Linoan has this spiritual noble bearing to her, she still is "Le Headstrong Woman" and has a way of convincing people to do what she wants them to do, and isn't above gossip either (even being subjected to it in the epilogue). He however deeply values those around her and wishes for everyone's well-being before her own.
Dean
I god damn love this guy. He is a prepromoted Wyvern Lord, and he does what they do best: Destroy and Carry. He's almost invincible and is as tanky as a General. He's also got 3 FCC and access to every Lance and Sword in the game at base. He's probably one of the best units in all this game, and if we take away my personal bias, probably THE best. I mean, he flies, he can capture reliably too, and he's got amazing stats. What else do you want out of a unit?
He's a calm and collected guy, most of the time. Dean, despite his chill facade, actually knows how to behave around people, since he is shown to have comforted Linoan for a long time and made her feel better about herself. His little sister also looks upon him as a role model, and idk, I think I see why people in-universe like this guy. He is fiercely loyal to his home-country but even then, he doesn't fight alongside it in order not to fight against his own friends. Dean is just a really cool guy, my second favorite Thracia 776 exclusive character. He only loses to one specific character to me.
Sara
Ah, here she is! Sara is another cleric just like Linoan who joins under leveled with amazing growths. Kinda sounds like an Est archetype, right? Those late-joining units who have bad bases but their growths are great? Well, the difference here is that Sara... actually has really good bases that are even good at the point where she joins, and her growths are mostly at 80%, and she has Wrath, and PARAGON, a skill that doubles Exp gains. She very quickly snowballs into a monster, and easily becomes one of the best combat units on your team. But that's not all. She can use staves. She has a B rank at base, meaning that when she promotes, she's able to immediately use Warp Staves, and all kinds of good staves. She was the unit I had the most fun with period.
She's also a really cute character in general. Sara appears pretty shy, and even says weird things from time to time. She's so aloof and detached, but when she actually speaks full sentences her dialogue is just so quirky and funny at times, even. But there's also a hint of tragedy since she's the freaking granddaughter of MANFROY of all people and I still can't believe that such an adorable thing can be related to that horrible sin of a man. She's nothing at all like him. Poor girl. I love her tho. She just needs a good and warm hug.
Ced
Ced returns from FE4, and he's as strong as ever! He comes with the almighty FORSETTI! That alone makes him amazing but he also comes with A rank staves, so you know he'll help you cheese the few annoying maps to come. Not much else to say, he's just awesome.
He's pretty much the same guy as in FE4, although here you see a supportive side of him, and how uplifting he is. He also has the makings of a great king, just like his father, and has a rallying spirit. A great guy, basically.