Fire Emblem Engage lets you pair your units with Lords from previous games through the Emblem Rings system. Doing so enhances your characters with stat buffs and skills.
All your units can equip these rings, which creates a massive level of customisation for you. It should be noted that all of the Emblem Rings can and should be swapped around frequently to find a pairing that works for you, but some pairings are indisputably better than others.
Spoiler Warning: One of the characters who joins your army could be considered a significant spoiler, and they are listed below.
13 Alear And Roy
Emblem Roy is about increasing your strength and resistance stats, while also adding a decent layer of survivability to any character paired with this ring. Alear and Roy go together well because of this, allowing Alear to survive any potential one-shot damage thanks to the Hold Out skill.
If you want Alear to deal more damage at the cost of speed, this is the pairing for you. Furthermore, Roy's other innate skill adds five levels to your character and a bunch of HP as you level up the bond rank. To top it all off, Roy's Engage Skill, Blazing Lion, gets more range when used by Alear.
12 Diamant And Ike
Diamant is effectively Ike by another name in Fire Emblem Engage, and it seems criminal to pair them with any other Emblem. Ike's bonuses increase defence, strength and HP, and the number increases the higher Bond rank you have. Along with this, while Engaged with Ike, you get access to his skill Laguz Friend, which reduces all incoming damage by 50 percent.
This pairing is perfect for Diamant and his class skill Sol, especially when the two are synced. Laguz Friend will reduce damage and keep him on the frontlines, while his Class Skill will occasionally trigger and restore his HP with a hit. It's an incredibly strong pairing, making Diamant even harder to kill.
11 Merrin And Lucina
Merrin has a ton of innate speed and dexterity, which will be enhanced when she's paired with Lucina. Better yet, while Engaged, Merrin will benefit exceptionally from Lucina's Dual Strike skill. This skill will make Merrin act as a backup unit, which means if she's in range of an enemy your ally is attacking, she will jump in with a Chain Attack.
This is even more broken on Merrin as a Wolf Knight since she will have a lot of movement range, and she can attack two spaces with knives. Effectively this means she will Chain Attack every single time if she's Engaged with Lucina and in range of your allies.
10 Louis And Ike
Louis has some of the best defence growths in the game, but he has a gargantuan struggle when it comes to resistance. The idea behind this pairing is to make up for that lack of magic defence by using Ike's Laguz Friend skill while Engaged. If you use Louis on your frontlines to keep enemies away from your weaker units, you'll want to Engage with Ike at the right moment.
This is, of course, whenever a mage is in combat range and ready to blast Louis into oblivion. Laguz Friend helps him survive a heck of a lot and will bolster his defence to the point where physical enemies will do either low damage or nothing at all. The HP and strength gains from levelling up his Bond while wearing the Ring will also enhance what's already great about Louis.
9 Fogado And Roy
For the same reasons listed for Alear, Roy is extremely useful to Fogado or any other strong cavalry unit. This is due to the type bonus the skill Rise Above adds to mounted units, giving them one more movement than normal.
Rise Above changes depending on which character type you have synced with Emblem Roy, and this is one of the better bonuses you can get from this skill. Fogado is a mounted archer, so you can imagine why more movement is beneficial to him. Not to mention most bow users can always do with more strength, which Roy more than adds to.
8 Jean And Micaiah
Pairing Jean and Micaiah can yield to you one of the better support units in the entire game. Keeping Jean as a Qi Adept will give him a type bonus while Engaged with Micaiah that lets Great Sacrifice cure status ailments, as well as increase the amount healed by staves. You don't even want Jean to be on the front lines, so he's perfect as a healer. This makes him one of the better ones in the game.
As a bonus to all of this, Jean acts as the Villager in Fire Emblem Engage, which means he comes with the skill that adds an increased chance to all his stats levelling up. Since you get Micaiah early in the main story, you can abuse her Engage Skill Great Sacrifice to get a bunch of levels for Jean without having him use all your healing or risk dying in combat.
7 Yunaka And Corrin
Thief units are classified as Covert, which doubles your unit's Avoid bonus from terrain effects. Yunaka pairs exceptionally well with Corrin because now she can create her own Avoid Tiles using Corrin's Dragon Vein ability every turn.
On top of that utility, Yunaka's Personal Skill increases her critical hit chance by 15 percent while she's on terrain that provides an Avoid bonus. This will effectively turn Yunaka into a hard-to-hit critting machine. Corrin's pairing doesn't do a whole lot for Yunaka's lack of damage, but she can be an excellent avoid tank this way.
6 Veyle And Celica
Veyle doesn't join your ranks until the last few chapters of the game, but she's one of the stronger dagger users you'll have. She has a unique class that utilises magic and knives, but her special weapon, Misericorde, scales off her magic stat. Pairing her with Emblem Celica enhances her magical attacks and gives her access to Warp Ragnarok.
Celica is an all-around buff to Veyle since she already hits so hard with her magic. This can be further exploited by using Echo, Celica's special ability, which allows you to attack twice at the cost of half damage.
5 Chloe And Eirika
Emblem Eirika is excellent for keeping several weaker units alive and topped up. Pairing a unit like Chloe with Eirika, which will provide the Lunar Brace and Gentility skills, and the Solar Brace skill while Engaged, will go a great distance in keeping Chloe on the frontlines by taking less damage and recovering her own HP.
The Gentility skill reduces incoming damage by a flat three points, and on top of that, you get a boost to Avoidance just by wearing her Ring. Furthermore, Chloe can use swords and more powerful weapons while Engaged, all of which will keep Chloe's damage up as you progress through harder maps.
4 Alear And Marth
Fire Emblem Engage forces this pairing down your throat from the start of the game, and for a good reason. Emblem Marth is geared toward your all-rounder characters, turning your decent units into excellent ones with the benefits and bonuses he provides.
Marth's synced skills, like Divine Speed and Break Defences, will add more offence to a character with weapon triangle advantage, as well as restore HP with the former skill. Thanks to the strength, speed, and dexterity bonuses, Alear and Marth will be a powerful combo no matter what happens.
3 Goldmary And Leif
Goldmary is one of the strongest units in the game, and she's one of the only Hero classes you'll have unless you promoted another one into it. This gives her access to Swords and Lances, which makes her perfectly versatile, especially when you pair her with Leif.
Leif's Adaptable ability comes in clutch and means you'll never lose a weapon triangle encounter while you're Engaged. Leif's skill Arms Shield also gives you a flat damage increase if you have a weapon triangle advantage, letting you deal more damage per hit. One of the best things about this pairing is Leif's increase to your Build, letting you use heavier weapons without a speed penalty.
2 Citrinne And Byleth
Byleth is versatile since he comes with essentially all of the best Relics and gear from Fire Emblem Three Houses. Your unit's class dictates which one you get, be it the Aegis Shield, the Blutgang sword, the Luin spear, and so on. The best of the best is pairing Byleth with a mage like Citrinne to give her the Thyrsus wand.
You'll remember the Thyrsus wand from Three Houses since it increases your magic range by two spaces. We shouldn't have to explain why this is so incredibly busted for your mage characters, especially if Citrinne has Canter. Thyrsus alone is worth it to pair with Byleth, with everything else being a happy bonus.
1 Alcryst And Lyn
Lyn works best with everyone's favourite inferiority complex archer, crown prince Alcryst. They are arguably the best pairings in the game due to how speed-orientated her kit is. Lyn can give you the Alacrity skill, which is perfect on any unit, but it shines brightest with Alcryst.
He's already one of the best archers you'll get, and with Alacrity, he will be nearly untouchable so long as he initiates combat. Alacrity lets you perform your follow-up attack before the enemy can attack, so long as you have more than nine points of speed than them. When Engaged with Lyn, Alcryst gets ten plus more range when using her Engage Skill Astra storm, which means you can snipe fools from across the map.