Sumner sits next to 5 phonetic neighbors — Summer, Spencer, and Gunner are the closest matches by sound. Most share Sumner's English-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"summoner, one who calls forth"
"handsome, distinguished"
"twin (loose association)"
"from the lake"
"supplanter, held by the heel"
"warrior, military companion"
"red-haired, ruddy complexion"
"brother, friend"
"great tide, sea current"
"of Tyre, the ancient city"
"settlement on the River Ren"
"from Hadria, dark and rich"
"son of Lars"
"vigilant, watchful"
"son of the gray-haired one"
"God is gracious"
"bright, splendid"
"forward-moving, avant-garde"
"fair-haired one"
Similar sound: These names share phonetic patterns with Sumner — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old French origins, giving them the same cultural heritage as Sumner.
Rhythm: Sumner is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.