Felix sits next to 4 phonetic neighbors — Phelix, Alexi, and Dexter are the closest matches by sound. Most share Felix's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"happy, fortunate"
"divine strength"
"supplanter"
"traverser, one who crosses"
"griffin (mythical lion-eagle creature)"
"man from Lucania"
"between two hills"
"fortunate, prosperous"
"From the Scottish place name Logan; a topographic name from Gaelic ..."
"tumult, noise"
"muddy place, ditch"
"God has given"
"my God is the Lord"
"son of Gray"
"handsome at birth"
"from the people (damos)"
"strong, virile"
"God is gracious"
"son of Carr (marsh dweller)"
"dark one, black"
"broom-covered hill"
Similar sound: These names share phonetic patterns with Felix — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Felix.
Rhythm: Felix is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.