Cletus sits next to 3 phonetic neighbors — Clive, Curtis, and Titus are the closest matches by sound. Most share Cletus's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"called forth, gloriously summoned"
"gift of the ocean"
"red king"
"hare's meadow, hare clearing"
"worthy of love"
"God will establish; may God protect"
"green, blooming"
"son of the fair one"
"small, little"
"of noble birth"
"gentle, mild-mannered"
"flat piece, thin layer"
"servant of St. Fillan"
Similar sound: These names share phonetic patterns with Cletus — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek origins, giving them the same cultural heritage as Cletus.
Rhythm: Cletus is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.