Lucius sits next to 4 phonetic neighbors — Lucas, Lukas, and Julius are the closest matches by sound. Most share Lucius's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"light, illumination"
"the fifth"
"land of Eoghan (Owen)"
"thunder ruler, powerful"
"crew, team"
"river traveler"
"son of Peter (son of the rock)"
"rock hill, old hill"
"noisy disturbance, civil commotion"
"my God is help"
"born of fire (head of fire)"
"mill town, settlement by the mill"
"young male horse"
"diminutive of Scott"
"serpent's mouth"
"illuminance unit"
"strength of God"
"love of God"
"will, desire, helmet"
"mighty peace"
Similar sound: These names share phonetic patterns with Lucius — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Lucius.
Rhythm: Lucius is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.