Jacen sits next to 5 phonetic neighbors — Jason, Jaden, and Jayson are the closest matches by sound. Most share Jacen's Greek-origin cluster, so the rhythm and vowel shape carry across the list.
You searched for names like
"healer"
"rock, mass"
"battle, warrior chief"
"tree, oak tree"
"Italian form of John"
"wise one (from Sionann mythology)"
"poet, bard"
"son of Rhys, ardor and enthusiasm"
"joyful outcry"
"the kingdom of Ciar, County Kerry"
"arbitrator, decider"
"from the Lennox region of Scotland"
"pledge, oath"
"archer, bow-wielder"
"hollow, cauldron"
"the Lord is my God"
"of the Tiber River, son of the Tiber"
"horseman, cavalryman"
"modern invented name"
"flat-topped hill settlement"
"the koa tree (strength)"
Similar sound: These names share phonetic patterns with Jacen — similar vowel sounds, consonant clusters, or rhythm.
Shared roots: Several names on this list have Greek origins, giving them the same cultural heritage as Jacen.
Rhythm: Jacen is a 2-syllable name. Names with the same syllable count tend to feel interchangeable when you're narrowing your list.