Hm, how is Conquest with child units?
I've hit an amusing point where I keep spawning Paralogues after Chapter 12, and everyone on my core team gained 3-4 levels between these chapters already thanks to those Paralogues auto-scaling, so I'm getting several early child units now. Already got Felicia!Percy (HP+5 and Tomebreaker) and Elise!Kana (Sol and Demoiselle) and both of those seem like solid, worthy additions to my core squad. Now if Effie!Sophie, who I expect to be a defensive powerhouse, will be a worthy addition is... debatable. Need to do that Paralogue first (which will probably push Odin and Selena to S rank meaning I'll need to get Ophelia, too...) before I can assess her.
I feel like getting Percy and Kana this early might actually make them worth investing in. Heck, Percy came with capped Luck at level 12 and almost as many HP as Camilla. A Tomebreaker Wyvern Rider just seems unfair somewhere, and getting Sol onto Kana who also has her own healing skill makes her pretty durable. Between a Dragonstone and a Nohrian Blade, she can take a hit, too. When your Def is higher than your Level, you're in fine shape.
Also, Percy is voiced by the same person who voices Pit in Kid Icarus Uprising, right?