This is my first Fire Emblem, so I'm a little lost with some aspects of the game.

Because I like challenges in my games I picked the mode which allows character permadeath. The first battle you're thrown into is a practice battle where your characters don't die but return after the battle finished. When I continued playing after I think I misunderstood this aspect and took it as "permadeath is only possible in story missions" and thus did not rewind time when a character died in one of the "Optional Battles" I did a little while after.

I picked the Golden Deer House in the beginning and I now have the following characters in my roster:
Claude
Hilda
Lorenz