Dartagnan sits next to 3 phonetic neighbors — Tarquin, Damian, and Alistair are the closest matches by sound. Most share Dartagnan's French-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"from Artagnan, a village in Gascony, France"
"to travel leisurely"
"set apart, holy"
"bright settlement"
"from the land"
"descendant of Nuallán"
"one thousand million, immense wealth"
"goodness of God"
"lake colony, Roman settlement by the pool"
"patient, steadfast, enduring"
"gift of God"
"from Leamhanaich (elm grove place)"
"crowned with laurel, victorious"
"wolf by the stream or pool"
"God has remembered"
"island"
"Saxon's settlement, Saxon town"
"one who covers"
"ruler, sovereign (Greek/Latin influence on Tyrant root)"
"precious, greatly valued thing"
Similar sound: These names share phonetic patterns with Dartagnan — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have French origins, giving them the same cultural heritage as Dartagnan.
Rhythm: Dartagnan is a 3-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.