Atreyu sits next to 3 phonetic neighbors — Tre, Drayco, and Arayu are the closest matches by sound. Most share Atreyu's German-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"invented name; possibly son of the fearless one"
"swift projectile, arrow"
"brave ruler, strong king"
"great house"
"variant of Pearson: son of Piers"
"coastal land, border land"
"fortunate, good luck"
"ruler of peace"
"old town, settlement"
"western town, western settlement"
"servant of God"
"life"
"scarce, seldom"
"salvation of the Lord (via Isaiah element)"
"rush plant (marsh grass)"
"divine, god"
"ruler of the world"
"father of peace"
"Jehovah supports"
"sky, heavens"
Similar sound: These names share phonetic patterns with Atreyu — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Fictional (Michael Ende, 1979) origins, giving them the same cultural heritage as Atreyu.
Rhythm: Atreyu is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.