Karsen sits next to 5 phonetic neighbors — Carson, Carsen, and Larsen are the closest matches by sound. Most share Karsen's Old Norse/Scottish (via Carson)-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"son of Carr, son of the marsh dweller"
"from Galloway"
"one touched by good fortune"
"son of Bray (from Celtic bray: brave)"
"advice, counsel"
"raven's island"
"son of Rand, son of the shield-wolf"
"follower of Christ"
"bright, shining"
"heart, spirit"
"horseman, from the Cheviot hills"
"greatest stream (via Maxwell)"
"guiding spirit"
"from Airelle (a place in Normandy)"
"of the angel, messenger of God"
"safe, unharmed (proposed etymology)"
"good race, fine stock"
"old friend"
"modern invented American name"
"held by the heel"
"well-spoken, good word"
Similar sound: These names share phonetic patterns with Karsen — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Old Norse/Scottish (via Carson) origins, giving them the same cultural heritage as Karsen.
Rhythm: Karsen is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.