Mervin sits next to 3 phonetic neighbors — Marvin, Merlin, and Melvin are the closest matches by sound. Most share Mervin's Welsh cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"marrow of the sea, sea fortress"
"brave"
"enlightened rice (kanji: 悟飯)"
"spiritual essence, animating force"
"sea of bitterness, drop of the sea"
"phonetic rendering of initials J and C"
"wise power"
"son of Ole (ancestor)"
"Majestic, inspiring reverence"
"Sacred to Juno"
"salt"
"forest friend, house friend"
"The sky, heavens"
"free ruler, powerful peace"
"unity, excellence, number one"
"of the Tiber River, son of the Tiber"
"graceful, elegant"
"Patrick's town, fighter's settlement"
"God smiles"
"divine, godlike (Sanskrit)"
"possibly fire-derived (East Asian linguistic inspiration)"
Similar sound: These names share phonetic patterns with Mervin — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Welsh origins, giving them the same cultural heritage as Mervin.
Rhythm: Mervin is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.