Lucien sits next to 4 phonetic neighbors — Lucian, Lucius, and Julian are the closest matches by sound. Most share Lucien's French-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"light, luminous"
"strong, virtuous, honorable"
"tile maker (short for Tyler)"
"primordial deity, elder god"
"brave, bold"
"helmet of will, guardian"
"vigorous, flourishing"
"narrow water"
"one who has made pilgrimage to the Holy Land"
"great forest, eagle valley"
"son of Neil, son of the champion"
"settlement at the inhospitable place"
"woodland"
"remedy, cure (folk etymology)"
"my strength is Yahweh"
"God is my help"
"little warrior"
"short form of Benedict: blessed"
"variant of Carson"
"open grassy land"
"one from the British Isles"
Similar sound: These names share phonetic patterns with Lucien — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Latin origins, giving them the same cultural heritage as Lucien.
Rhythm: Lucien is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.