Aleksei sits next to 4 phonetic neighbors — Alexei, Aleksey, and Alexis are the closest matches by sound. Most share Aleksei's Russian-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"defender of mankind"
"of Mars, little warrior"
"gift from God, God given"
"rib, side"
"strife, discord"
"God is gracious"
"greatest (Ukrainian form)"
"son of the lion"
"the hidden one, lady"
"consecrated to Mars"
"upright post, beam"
"devoted to Demeter"
"victorious one"
"healer"
"first among thinkers"
"well-pleasing, excellent"
Similar sound: These names share phonetic patterns with Aleksei — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek origins, giving them the same cultural heritage as Aleksei.
Rhythm: Aleksei is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.