Alexei sits next to 5 phonetic neighbors — Alexis, Aleksei, and Alexey are the closest matches by sound. Most share Alexei's Russian-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"defender, helper of mankind"
"manly, brave, virile"
"iron-willed, strong"
"associated with Vladimir Lenin, revolutionary leader"
"flame, bright"
"of the Caspian Sea"
"who is like God? (no one!)"
"champion of the people"
"destroyer of peace"
"people's triumph"
"gift of God"
Similar sound: These names share phonetic patterns with Alexei — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek 'alexein' origins, giving them the same cultural heritage as Alexei.
Rhythm: Alexei is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.