Fire Emblem Heroes has over 125 playable characters (yet here am I griping about not having Ike and Boey). There's always the potential for more, especially from Path of Radiance:

The guy with green hair at the bottom left? I think that's Sothe. The red hair girl next to Sothe is named Jill. Despite looking like an Anna.

And Radiant Dawn. Especially if you take away repeats. And Sanaki, because she is already in the game with Ike, Mist, Titania, and Soren.

I played both games but didn't get far because I kept killing off the main heroes.

But we could herons, hawks, tigers, falcones, cats, lions, more dragons, and wolves to Fire Emblem.

Did you notice the one guy that looked like Subaki?

That's Shinion, who hates Ike and refers to Laguz as sub-humans. Kind of makes me want to have Subaki kill him, even though Subaki is a pegasus knight. Just send Robin after him? Robin, kill racist Subaki! 

Rolf is Boyd and Oscar's younger brother who looks like Gordin. I shipped him and Mist, but she married Boyd..... Who insulted her weight and made her shove him three spaces on a map in the middle of a chapter. Also, he and Ike tend to fight. A lot.

Mist, pick a better guy. Like Rolf.

This is the sister of Lethe, another cat Laguz. I want to pet them both.

Okay then, maybe not.

All of these images are from the Fire Emblem wikia

I might do another chapter describing characters, like "Laura is weak but can use light magic if you invest in her" or "Elicinia married her wet nurse's son, who was raised with her.