Brother for Theo and Lyra?

I need help coming up with a name for a minor character of mine. He’s not very important to the plot of the story, but he does appear in numerous scenes. He’s the youngest of three children (the others being, obviously, [name_u]Theo[/name_u] and [name_f]Lyra[/name_f]). I’m currently considering [name_m]Xander[/name_m] for several reasons: one, because it’s two syllables like both [name_u]Theo[/name_u] and [name_f]Lyra[/name_f], and two, because all three names are of Greek origin (though this has no relevance in the story at the moment, it ties them together for me in a nice way). However, I’m not sure I like it for him.

Perhaps I’m overthinking it, especially considering he isn’t a main character. Really, I’m just looking for a second opinion. My question is, if you wouldn’t use [name_m]Xander[/name_m], what name goes well with the other two to you?

I like [name_m]Xander[/name_m] and it could be short for [name_m]Alexander[/name_m] and so could [name_u]Alex[/name_u], but if you don’t like that you could try [name_u]Dexter[/name_u] nn [name_m]Dex[/name_m] if that works for you.